MILITARY 
SIGNAL  CORPS  MANUAL 


COMPILED  BY 


MAJOR  J.  ANDREW  WHITE 

Chief  Signal  Officer.  American  Quard;  Member,  Institute  of  Radio 

Engineers;  Acting  President,  National  Wireless  Association; 

Editor,  The  Wireless  Age;  Director  of  Vocational 

Training,     The    Marconi    Institute 


260  Illustrations 


WIRELESS  PRESS,  Inc. 

25  Elm  Street, 
New  York. 


Copyright,  1918 

by 
WIRELESS   PRESS,   Inc. 


CONTENTS 

Part    I. — Organization 

The  Signal  Corps— An  Auxiliary  Branch  of  the  Army. .  1 

The  Signal  Corps'  Relation  to  the  Line  of  the  Army..  4 

Aircraft    

Government   and  Administration 11 

Military  Courtesy   13 

Personnel    20 

Proficiency  Test  for  Companies  of  Signal  Troops 22 

Part   II. — Drill   Instruction 

General  Principles    24 

Definitions   28 

Commands  and  Signals • 30 

School  of  the  Soldier 45 

Physical  Training 52 

School  of  the  Squad 70 

Instruction  with  Arms 76 

>,  The   Company  Dismounted 81 

°|  The  Soldier  Mounted 84 

o|  Elementary  Collective  Instruction  Mounted 112 

33  Field   Signal  Troops 117 

2*  The  Wire  Company 118 

Hi     The    Radio    Company 140 

C3     The  Outpost  Company 153 

2     The   Field   Battalion .". 177 

-^Telegraph  Signal  Troops 181 

The  Telegraph   Company 183 

The  Telegraph  Battalion 215 

Base  Line  Signal  Troops 217 

Depot   Signal  Troops 220 

Ceremonies 221 

Reviews   222 

Inspections     228 

Funeral  Escort 234 

The  Standard   236 

The  Guidon    237 

Manual  of  the  Saber : 238 

Part  III. — Technical   Instruction  and  Apparatus 

Telegraphj'  and  Telephony. 
The  Voltaic  Cell,  Ohm's  Law  and  Primary  and  Secondary 

Batteries  .  ..242 


340616 


The  Camp  Telephone  and  the  Buzzer 261 

Induction  Telegraph  Set. .  .300 

Radiotelegraphy    •  • 305 

Radio  Apparatus  of  the  Signal  Corps 390 

Visual  Signaling  Equipment. 

Flag  Kits  428 

The  Heliograph   431 

The  Acetylene  Lantern 436 

Technical  Equipment  of  Personnel 441 

Part    IV. — Transmission 

Transmission  of  Military   Information 442 

General  Instructions  for  Army  Signaling 445 

The  American  Morse  Code. 447 

The  International  Morse  or  General  Service  Code 449 

Instruction  in   Garrison. 

Visual  Stations  452 

Telegraphy 452 

Visual  Signaling  in  General 461 

Signaling  by  Flag,  Torch  and  Lantern,  or  Beam  of  Search- 
light (Without  Shutter) 463 

Signaling   with    Heliograph,   Flash    Lantern,    or    Searchlight 

(With  Shutter)  465 

The  Ardois  System 466 

Signaling  by  Two-Arm  Semaphore 468 

Signaling  by  Hand  Flags 470 

General    Instructions    for    Locating    and    Operating    Visual 

Stations   573 

Letter  Codes  476 

Telegraph  Code  Books  and  Ciphers 480 

Conventional  and  Preconcerted  Signals  with  Rockets,  Bombs, 

Small  Arms  and  Guns .485 

Flag  Signals  by  Permanent  Hoist 487 

Emergency  Signals  488 

Conventional  Telephone  Signals 490 

Part  V.— Field   Service 

Signal  Troops  in  the  Field 491 

Reconnaissance,  Patrolling  and  Scouting 497 

Military  Map  Reading 503 

Signal  Troops   in    Field   .Service ••....521 

Field  Lines 524 

("amps    .  • • 531 

Company  Guard  M ounting •  - 549 

The  Signal  Corps  and  General  Coast  Defense 549 

Coast  Defense  Information   in   War... •• ..558 


PART  I-ORGANIZATION 

THE  SIGNAL  CORPS— AN  AUXILIARY  BRANCH  OF  THE 

ARMY 

It  is  common  knowledge  that  a  soldier  is  a  fighting  man  whose 
services  are  due  to  the  state ;  that  in  the  regular  army  there  are 
soldiers  of  infantry  who  march  and  fight  on  foot,  cavalry  troopers 
who  ride  horses,  and  artillery-men  who  serve  the  guns.  It  may 
even  be  known  that  engineer  troops  exist  who  belong  to  the  line 
and  perform  the  ordinary  duties  of  the  soldier  in  addition  to  their 
special  service  as  engineers. 

But  how  few  people  realize,  even  if  they  know,  that  attached  to 
all  armies  there  must  be,  in  addition  to  the  men  whose  first  duty 
is  to  fight,  other  bodies  of  troops  whose  services  are  absolutely 
needed  for  the  proper  conduct  of  military  affairs ;  soldiers  who 
are  combatant  troops  but  are  charged  primarily  with  duties  tech- 
nical in  character  and  requiring  special  training  and  organization. 

It  is  little  known  in  fact  that  in  every  properly  organized  army 
there  exist,  in  addition  to  the  men  who  carry  a  rifle  or  a  saber  or 
who  man  the  guns,  certain  auxiliary  and  special  troops  upon  whom 
the  success  of  the  campaigns  depend,  and  by  whose  services  alone 
can  the  general  in  command  hope  to  intelligently  meet  his  enemy 
and  oppose  him  with  an  adequate  force  properly  supplied  with  food, 
ammunition,  and  the  thousand  needs  of  an  army.  These  troops  are 
not  as  essential  to  success  when  the  shock  of  contact  comes  as  are 
the  guns  and  sabers  of  the  fighting  line,  nevertheless  they  are  indis- 
pensable to  every. armed  force  and  without  their  aid  no  mobility 
can  exist,  no  battle  be  engaged,  no  knowledge  of  conditions  be 
obtained.  An  army  fights  with  its  guns,  therefore  it  must  have 
powder;  in  these  days,  too,  it  fights  with  its  brain  and  the  brain 
must  be  informed.  In  the  United  States  Army  this  last  function — 
that  is,  the  service  of  military  information — is  placed  in  charge  of 
one  corps,  the  Signal  Corps  of  the  army.  The  service  thus  concen- 
trated and  not  scattered  among  several  branches  of  the  army  vary- 
ing in  intelligence,  instruction  and  experience,  as  is  the  case  gen- 
eraly  abroad,  is  believed  to  have  an  advantage  in  consolidation  that 
has  not  only  been  proved,  but  that  is  increasing  with  the  steady  ad- 
vances in  the  science  of  war. 


2  MILITARY  SIGNAL  CORPS  MANUAL 

Few  people,  however,  know  the  character  of  this  corps,  fewer 
still  the  service  it  performs,  the  scope  of  its  duties  or  the  reasons 
for  its  existence ;  the  name  but  vaguely  indicates  the  nature  of  its 
work.  Since  the  creation  of  a  Signal  Corps  in  the  early  days  of  the 
civil  war,  its  then  simple  functions  have  greatly  increased  in  scope 
and  variety  and  its  usefulness  has  been  enormously  enlarged  until 
now  it  is  evident  that  the  importance  of  this  service  in  military 
affairs,  its  necessity  in  the  control  of  armies  in  the  field,  and  its 
paramount  value  in  the  conduct  of  war  have  been  proven  beyond 
a  doubt.  Indeed,  it  is  hardly  too  much  to  say  that  the  great  exten- 


One  method  employed  by  the  Signal  Corps  in  acquainting  a  commander 
with  knowledge  of  events  as  they  occur,  is  illustrated  here.  Above  is 
shown  the  operation  of  the  combined  telephone  and  telegraph  buzzer;  to  the 
right  a  mounted  man  with  pike  used  to  lay  the  wire;  lower  left,  a  militia 
motorcycle  with  supplies,  and  lower  right,  a  signalman  receiving  firing  data 

sion  of  fighting  lines,  the  destructive  power  of  enormous  engines 
of  war,  and  the  control  of  the  master  mind  seen  in  the  present  war 
of  the  nations,  are  made  possible  not  only  by  the  advance  in 
mechanical  arts  but  by  the  harnessing  of  electricity  and  by  modern 
methods  of  transmitting  intelligence,  which  we  call  the  transmission 
of  military  information.  It  is  true,  however,  that  all  this  is  merely 
a  growth, and  though  to  the  fighting  man  the  need  of  information 
is  more  urgent  now  than  in  the  earlier  days  as  the  size  and  power 
of  armies  increase  and  the  control  of  the  master  mind  grows  more 


A\  Ai -XILIARY  BRAXCH  OF  THE  ARMY  3 

imperative,  the  fundamentals  have  not  changed  since  man  became 
a  thinking  animal.  The  first  need  of  a  commander,  now  as  then, 
is  a  knowledge  of  events  as  they  occur,  and  of  conditions  as  they 
exist.  To  transmit  this  knowledge,  no  matter  how  obtained,  is  in 
brief  the  primary  function  of  the  Signal  Corps. 

The  service  of  the  lines  of  information  has  become  a  major 
factor  in  the  conduct  of  military  affairs,  if  it  is  not  now,  indeed, 
the  paramount  element  in  the  control  of  modern  wars.  Without 
information  and  knowledge  of  events  and  conditions  as  they  arise, 
all  else  must  fail. 

It  is  probably  true,  as  has  been  said,  that  the  art  of  war  has 
not  changed  with  the  passage  of  years,  but  it  is  true  that  the  science 
of  war  has  changed  enormously  since  the  days  of  the  muzzle- 
loading  guns,  captive  balloons  and  messenger  service.  To  this 
change  perhaps  no  elements  have  contributed  more  effectually  than 
electricity  and  air  navigation,  which  are  the  two  functions  that 
permit  the  rapid  dissemination  of  information  regarding  events 
as  they  occur,  and  have  replaced  the  slow  groping  in  the  dark 
of  contending  forces  of  former  years.  With  the  use  of  these  ele- 
ments the  Signal  Corps  is  charged,  and  as  corps  it  may  be  said 
to  exist  for  one  main  purpose:  THE  SPEEDY  DISSEMINA- 
TION OF  MILITARY  INTELLIGENCE  OR  INFORMATION. 

It  has  other  duties,  but  the  exchange  of  ideas  in  military  affairs 
is  the  real  reason  for  its  existence.  It  is  the  nerve  system  of  the 
army  by  which  information  is  transmitted  to  its  brains. 

The  collection  of  military  information,  also  a  function  of  the 
corps,  though  important,  is  secondary,  since  it  is  a  duty  shared  by 
many  persons  in  and  out  of  the  military  service  and  does  not  belong 
to  the  Signal  Corps  alone. 

In  peace  the  Signal  Corps  is  concerned  with  the  manage- 
ment of  military  affairs  ;  in  war,  with  the  control  of  troops  and 
the  conduct  of  campaigns. 


THE  SIGNAL  CORPS'  RELATION  TO  THE  LINE  OF  THE 

ARMY 

The  Signal  Corps  in  reality,  though  not  in  law,  is  both  a  staff  and 
a  line  corps  and  must  be  trained  in  the  duties  of  both.  The  training 
for  service  with  troops  can  only  come  through  association  with  the 
line,  to  whom,  in  war,  the  signalmen  are  bound  as  closely  as  are  the 
three  arms  of  the  service  to  each  other,  for  it  should  be  remembered 
that,  like  all  staff  and  auxiliary  troops,  the  Signal  Corps  is  essentially 
an  adjunct  to  the  line  of  the  army  and  can  have  no  separate  exist- 
ence. Indeed  if  we  omit  its  special  functions  with  the  coast  defense, 
the  value  of  the  Signal  Corps  depends  solely  upon  the  use  made  of 
it  by  the  line,  and  this  in  turn  upon  the  knowledge  and  capacity  of 
commanding  officers,  to  whom  familiarity  with  the  scope  and  power 
of  the  corps  is  vital. 

The  means  of  acquiring  knowledge  of  the  use  of  a  Signal  Corps 
in  a  practical  way  are  few ;  field  exercise  is  almost  the  only 
school.  Theoretical  knowledge,  however,  may  be  acquired  by  other 
means  than  maneuvers,  and  such  knowledge  should  be  insisted  upon, 
but  instruction  should  not  begin  and  end  with  senior  officers.  As 
with  other  military  studies,  the  commencement  must  be  made  far 
down  the  scale  of  rank,  in  order  that  the  general  may  put  in  use 
instinctively  knowledge  the  beginnings  of  which  were  acquired  as  a 
subaltern.  Obviously  a  knowledge  of  technical  equipment  can  not 
be  acquired  between  sunrise  and  sunset. 

There  can  be  no  doubt  that  this  corps  in  training  should  be  asso- 
ciated as  closely  as  possible  with  the  line  of  the  army.  With  the 
training  of  these  troops,  their  methods  and  service,  the  signalmen 
must  be  familiar,  for  with  them  his  duties  in  war  will  be  intimately 
connected.  Signalmen  should  serve  habitually  with  troops  of  the 
mobile  army,  and  especially  with  the  field  artillery  for  whom  various 
forms  of  signal  apparatus,  the  radio,  and  especially  the  airplane 


RELATION  TO   THE  LINE  5 

become    most    important    auxiliaries,    as    have    the  telephone,    the 
buzzer,  and  pyrotechnics. 

In   addition,    detachments   of    signalmen    should  perform    many 

duties   in   connection   with    the   coast   defense   and  its   auxiliaries. 


The  wireless  "Service  of  Information"  at  work  in  Mexico.  Signal  Corps 
men  in  actual  service  are  shown  here  maintaining  communication  between 
the  flying  cavalry  column  and  the  headquarters  of  the  American  punitive 
expedition 

Beside  these  two  fields  of  work  lies  the  still  undefined  service  of 
the  coast  guard  where  the  field  apparatus  of  the  Signal  Corps — the 
land  cables,  the  buzzer,  radio,  airplane,  and  perhaps  the  dirigible  and 
captive  balloon — perform  a  large  and  important  function  in  the 
defense  of  the  country. 

In  addition  to  a  general  knowledge  of  the  methods  of  transmit- 
ting military  information,  it  appears  that  reasonable  familiarity  with 


6  MILITARY  SIGNAL  CORPS  MANUAL 

the  instruments  and  methods  employed  under  varying  circumstances 
must  be  possessed  by  those  who  will  use  them  in  the  field,  and  espe- 
cially by  those  in  control.  It  is  evident,  for  instance,  that  no  officer 
about  to  assume  command  of  an  army  or  of  an  expeditionary  force 
for  service  in  a  distant  country  would  willingly  lack  information 
regarding  the  kinds  of  communication  that  should  be  used  in  the 
work  before  him  and  of  the  types  of  instruments  necessary ;  nor 
would  he  care  to  leave  the  selection  of  the  means  of  establishing 
his  lines  of  information  solely  to  the  judgment  of  a  subordinate, 
perhaps  a  stranger.  He  should  know,  from  the  nature  of  the  coun- 
try and  the  probable  scope  of  his  future  operations  the  character 
of  the  lines  that  he  will  need  and  the  kind  and  amount  of  material 
that  he  will  use,  and  must  provide  himself,  within  the  limits  of  his 
transportation,  with  everything  that  experience  and  knowledge 
may  suggest  as  useful.  For  that  reason  he  should  know  general- 
ly the  amount  of  material  to  select,  the  type  of  lines  of  informa- 
tion to  be  established,  and  the  number  and  kind  of  men  necessary 
to  use  them.  The  commanding  officer  will  have  a  signal  officer 
on  his  staff,  no  doubt,  to  whom  all  details  should  be  intrusted, 
as  he  will  have  an  ordinance  officer  and  an  engineer,  or  a  quarter- 
master ;  but  he  should  assure  himself  personally  that  his  means 
of  transmitting  information  are  sufficient  for  the  work  ahead, 
that  they  conform  to  his  plans  and  to  the  probable  field  of  action, 
just  as  of  his  own  knowledge  he  will  make  sure  of  the  arms  car- 
ried by  his  men,  the  type  of  his  artillery,  the  amount  of  his  ammuni- 
tion, the  size  of  his  pontoon  train,  and  the  character  of  his  ration. 
This  preparatory  work  of  a  commander  implies  some  knowledge 
of  the  service  of  the  lines  of  information  and  of  the  instruments 
used,  but  only  knowledge  of  a  general  nature.  It  is  after  he  takes 
the  field  that  his  capacity  and  experience  are  called  fully  into  play. 
Then,  indeed,  in  addition  to  his  own  knowledge  he  will  require  all 
the  assistance  that  the  most  skillful  of  his  signal  officers  can  render 
in  determining  the  kind,  scope,  and  plans  of  the  lines  of  information, 
distribution  of  men,  and  location  of  stations.  On  the  march,  in 
camp,  and  in  contact  with  the  enemy  such  dispositions  must  be  made 
by  him  as  to  not  only  secure  the  best  service  possible  for  himself 
as  commander  of  the  troops  or  expedition,  but  as  will  give,  also, 
to  those  in  subordinate  command  the  fullest  advantage  of  the  lines 
and  the  quickest  transmission  of  information  and  intelligence. 


AIRCRAFT 

The  Signal  Corps  is  intrusted  with  the  air  service  of  the  army — 
undoubtedly  the  most  important,  as  it  is  the  most  recent,  auxiliary 
in  the  collection  and  transmission  of  military  information.  It  has 
not  been  considered  wise  or  practicable  to  attempt  to  include  in 
this  small  volume  instructional  material  on  the  use  and  mechanics 
of  air  craft,  for  the  reason  that  the  subject  is  exhaustive  in  scope 
and  can  only  be  properly  mastered  by  personal  application — by 
actual  flying,  in  fact.  Some  definition  of  the  function  of  military 
air  craft  will  be  useful,  however. 

Air  craft  are  now  employed  for  strategical  and  tactical  recon- 
naissance and  the  prevention  of  reconnaissance  by  the  enemy's  air 
craft ;  for  the  direction  and  control  of  fire  of  the  field  artillery ; 
for  the  destruction  of  the  enemy's  personnel  and  material  by  ex- 
plosive and  incendiary  missiles  and  other  means;  and  for  the 
rapid  transportation  of  superior  commanding  officers.  The  value 
of  air  craft,  and  especially  of  the  airplane,  in  the  field  of  recon- 
naissance has  been  proved  beyond  the  shadow  of  a  doubt.  What- 


AX    EARLY   METHOD   OF    INSTALLING    THE    WIRELESS   AERIAL,   OR 
AXTEXXA,    OX    AX    AEROPLANE 


8  MILITARY  SIGNAL  CORPS  MANUAL 

ever  may  be  the  opinions  of  military  men  as  regards  the  offensive 
importance  of  air  craft  and  the  present  standing  of  the  dirigible, 
there  is  no  longer  a  question  as  to  the  value  of  the  airplane  in 
rapid  and  long-range  reconnaissance  work,  and  of  its  power  to 
secure  and  to  transmit  by  radio,  visual  signal  or  direct-flight, 
information  of  the  utmost  importance  to  armies  in  the  field.  So 
true  is  this  that  it  seems  probable  the  airplane  and,  to  some 
smaller  degree,  all  air  craft,  have  altered  not  the  principles  of 
strategy,  which  are  immutable,  but  the  theory  and  application  of 
grand  tactics. 

It  now  appears  that  the  actual  game  of  war  is  played  openly 
with  cards  laid  on  the  table,  and  opportunity  no  longer  is  given 
for  inference  as  to  concealed  movements  or  for  surprises,  perhaps 
not  even  for  the  exercise  of  the  high  military  quality  of  anticipa- 
tion of  the  unseen  movements  of  the  adversary.  It  is  now  recog- 
nized that  the  possibility  of  brilliant  and  unexpected  blows  and 
surprises  by  enterprising  commanders  has  been  largely  eliminated 
from  modern  operations  of  war  by  the  information  supplied  by 
the  aviators.  It  is  proved  that  the  modern  air  craft  lays  open  to 
the  field  of  mental  view  the  whole  visible  area  of  the  immediate 
theater  of  war  and  that  the  commander's  vision  reaches  far  beyond 
the  limits  of  the  actual  sight  of  his  marching  troops.  The  air 
craft  sees  and  indicates  the  larger  operations  of  war  and  points 
out  to  the  slowly  moving  men  on  the  ground  not  only  the  object 
to  be  attacked  or  defended,  but  to  reconnaissance  troops,  especially 
the  cavalry,  the  objective  to  be  sought,  the  localities  to  be  searched, 
and  the  character  of  information  to  be  obtained. 

By  no  means  does  the  air  craft  supersede,  nor  can  it  ever 
supersede,  the  work  of  obtaining  detailed  information  which  can 
be  acquired  only  by  close  observation,  by  contact,  and  by  develop- 
ment of  the  enemy's  forces  and  positions.  This  remains  the  duty 
of  the  troops  in  the  field ;  but  the  air  craft  does  indicate  to  either 
commander  the  character,  location,  and  general  disposition  of 
opposing  forces,  and  of  his  own  commands.  Not  only  has  it  been 
proved  that  the  airplane  is  invaluable  in  locating  the  position  of 
the  enemy,  but  it  has  especial  value  to  a  commander  in  finding 
his  own  troops,  in  keeping  him  informed  when  movements  are 
taking  place,  and  of  the  position  of  his  flanks  and  center,  his  out- 
posts, his  cavalry,  his,  artillery,  of  the  positions  attained  by  any 
detached  body — in  short,  of  keeping  him  constantly  in  touch  with 
the  locations  and  movements  of  all  the  units  of  his  command  under 
the  changing  conditions  of  war. 

This  much  is  proved,  but  it  does  not  follow  that  the  air  craft 
curtails  the  work  of  reconnaissance  of  other  arms  of  the  service, 
the  infantry,  the  Signal  Corps,  and,  more  especially,  the  cavalry. 


AIRCRAFT  9 

On  the  contrary,  it  extends  the  usefulness  and  power  of  all,  for 
if  the  general  field  of  reconnaissance  is  outlined,  it  is  obvious  that 
the  cavalry  or  infantry  can  more  readily  strike  its  objective  and 
more  quickly  and  accurately  obtain  information  regarding  any 
particular  point  than  if  obliged  unseeingly  to  search  the  whole 
field  of  operations  for  locations  and  forces  regarding  which  an 
intimate  knowledge  is  desired  or  contact  expected.  In  other  words, 
by  aid  of  air  craft,  and  more  especially  of  the  airplane,  a  recon- 
naissance by  troops  moves  less  in  the  dark,  knows  better  what  to 
look  for  and  search  in  detail,  and  loses  less  time  and  effort  in 
accomplishing  the  object  sought.  No  move  of  concentration  from 


AVIATORS    OF    THE    SIGNAL    CORPS    RECEIVING    INSTRUCTION    IN 
THE   ASSEMBLY   OF   AIR  CRAFT 

flank  or  center,  no  envelopment  of  a  wing  nor  re-enforcement 
of  a  weak  position  should  remain  unknown  to  the  adversary  in 
the  case  where  he  possesses  a  thoroughly  efficient  flying  corps.  It 
would  seem,  therefore,  that  not  only  has  the  power  of  all  recon- 
naissance troops  been  increased  by  the  air  craft,  but  also  that  the 
need  and  importance  of  the  cavalry  in  reconnaissance  work  have 
not  been  lessened,  but,  on  the  contrary,  have  been  greatly  increased 
by  them. 

In    addition    to    the    influence    exerted    by    air    craft    on    grand 
operations,  events  now  appear  to   show  that  their  value   in   more 


10  MILITARY  SIGNAL  CORPS  MAXTAL 

detailed  operations  is  great  and  may  increase  in  the  future  to 
enormous  proportions.  It  is  well  established  that  the  accuracy, 
value,  and  effect  in  service  of  field  and  siege  artillery  and,  indeed, 
of  the  heavy  guns  afloat  and  ashore  have  been  greatly  increased 
by  this  agency.  It  may  almost  be  said  that  guns  are  fought  by 
means  of  the  eyes  of  the  aviator.  So  clearly  has  this  been  shown 
that  there  now  appears  a  noticeable  change  in  artillery  practice. 
Instead  of  the  old-fashioned  system  of  range  finding  by  trial  fire 
or  of  observation  from  the  battery  or  elevations  near  by,  the 
exact  range  is  now  found  with  the  help  of  airplanes,  by  signaling 
positions  and  noting  the  fall  or  burst  of  the  shrapnel. 

Besides  influence  of  this  character,  the  airplane  has  undoubted 
use  in  the  finding  of  concealed  positions,  in  locating  hidden 
howitzers  or  mortars,  and  in  pursuit  and  rear-guard  actions.  It 
is  useful  in  the  location  of  ships  at  sea  or  at  anchor  within 
defenses,  in  the  detection  of  submarines  and  submarine  mines,  and 
certainly  in  the  enormous  increased  efficiency  given  to  seacoast 
gun  fire,  and  especially  to  the  coast  defense,  the  coast  guard,  and 
many  other  details  of  observation. 

But  the  useful,  approved,  and  most  important  work  of  air  craft 
is  to  be  found  chiefly  in  reconnaissance  and  the  collection  and  trans- 
mission of  information  in  the  theater  of  military  operations.  For 
this  reason  aviation  must  be  reckoned  as  a  vastly  important  branch 
of  the  Signal  Corps  of  the  army. 


GOVERNMENT  AND  ADMINISTRATION 

A  successful  commander  of  a  company  is  required  to  give 
time  and  attention  to  its  government,  just  as  if  it  were  a  busi- 
ness. The  supervision  required  naturally  divides  itself  into  two 
parts  :  government  of  the  command,  and  administration  of  its 
affairs. 

Government  is  represented  by  the  discipline  and  instruction 
and  the  harmonious  conduct  of  activities. 

Administration  comprises  the  provision  and  care  of  supplies 
and  equipment,  keeping  of  records  and  disbursement  of  com- 
pany funds. 

THE    CAPTAIN 

In  all  military  organizations  the  captain's  relation  to  the 
company  approaches  its  highest  ideal  when  he  is  considered  as 
the  father  of  a  large  family,  responsible  for  the  comfort  and 
personal  welfare  of  every  member  of  his  command,  looking  out 
for  their  development  and  providing  for  their  pleasure,  safeguard- 
ing their  health,  punishing  the  refractory  and  rewarding  the 
deserving.  By  superior  intelligence  he  is  expected  to  give  coun- 
sel to  his  men  and  display  every  interest  in  their  triumphs  and 
troubles.  The  progress  of  any  organization  will  largely  de- 
pend upon  the  captain's  conscientious  discharge  of  duty. 

But  the  captain  should  not  attempt  to  do  all  the  work;  far 
better  results  will  be  obtained  if  capable  subordinates  are  en- 
trusted with  full  responsibility  and  with  plenty  of  work  in  the 
duties  prescribed  for  them.  It  is  a  mistake  to  attempt  to  try  to 
command  every  squad  in  person,  subordinate  officers  with  prac- 
tically nothing  to  do  will  soon  lose  their  initiative  and  interest 
in  the  company.  Once  the  duties  of  officers  have  been  made 
clear  to  them  they  should  be  allowed  to  participate  as  fully  as 
practicable  in  the  government  and  administration,  they  should 
not  be  hampered  with  unnecessary  instruction  about  detail,  but 

11 


12  MILITARY  SIGNAL  CORPS  MANUAL 

f 

encouraged  to  learn  for  themselves  by  experience  the  art  of 
training  and  commanding  men.  Once  the  organization  is  well 
under  way  with  its  routine  work  the  captain  should  have  trained 
his  subordinates  so  well  that  he  will  be  able  to  give  a  large 
proportion  of  his  time  to  the  important  matters  of  discipline, 
instruction  and  welfare  of  his  command.  Captains  should  ex- 
ercise the  greatest  care  in  the  appointment  of  lieutenants,  for 
in  this  position  an  inefficient  officer  is  a  terrific  handicap  to 
overcome.  It  is  absolutely  essential  to  the  success  of  the  or- 
ganization that  the  lieutenants  be  held  to  strict  accountability 
for  results.  Lieutenants  incapable  or  unwilling  to  discharge 
their  duties  with  diligence  and  efficacy  have  no  place  in  a  body 
organized  for  military  training. 

THE   LIEUTENANT 

Primarily,  the  lieutenant  must  strive  to  fit  himself  to  be  able 
to  perform  every  duty  of  the  captain  when  that  officer  is  ab- 
sent or,  if  for  any  other  reason,  has  temporarily  given  him  full 
responsibility.  He  is  the  captain's  assistant  in  every  sense  of 
the  word  and  should  relieve  his  commander  of  work  whenever 
possible.  The  captain  should  require  him  to  drill  the  company, 
inspect  quarters,  instruct  non-commissioned  officers  and  thor- 
oughly acquaint  himself  with  all  duties  of  administration  by 
assisting  in  the  keeping  of  records  and  preparation  of  reports. 

Particular  attention  must  be  given  to  the  captain's  orders ; 
what  he  asks  of  his  lieutenants  personally  must  be  done,  not 
passed  along  for  execution  to  a  non-commissioned  officer.  The 
captain  will  give  his  order  direct  if  he  wants  it  executed  by  a 
non-commissioned  officer.  And  the  lieutenant  must  not  take  it 
upon  himself  to  make  sweeping  changes,  even  if  temporarily  in 
command,  especially  when  reduction  or  promotion  are  con- 
cerned the  captain's  wishes  should  always  be  consulted  in 
these  matters.  A  full  understanding  should  also  exist  on  the 
amount  of  authority  the  captain  is  willing  to  grant  to  his  lieu- 
tenants to  inflict  punishment,  assign  or  relieve  men  from  duty, 
in  the  absence  of  the  commander.  Permission  should  always 
be  secured  from  the  captain,  too,  if  the  lieutenant  wants  the  use 
of  a  working  party  or  any  supplies  not  regularly  distributed  for 
routine  work. 


MILITARY  COURTESY 

In  all  walks  of  life  men  who  are  gentlemanly  and  of  good 
breeding  are  always  respectful  and  courteous  to  those  about 
them.  It  helps  to  make  life  move  along  more  smoothly.  In 
civil  life  this  courtesy  is  shown  by  the  custom  of  lifting  the 
hat  to  ladies,  shaking  hands  with  friends,  and  greeting  persons 
with  a  nod  or  a  friendly  "Good  morning,"  or  other  pleasant 
phrase. 

In  the  Army  courtesy  is  just  as  necessary,  and  for  the  same 
reasons.  It  helps  to  keep  the  great  machine  moving  without 
friction. 

"Courtesy  among  military  men  is  indispensable  to  discipline; 
respect  to  superiors  will  not  be  confined  to  obedience  on  duty, 
but  will  be  extended  on  all  occasions,"  states  Par.  4,  Army  Reg- 
ulations, 1913. 

One  method  of  extending  this  courtesy  is  by  saluting.  When 
in  ranks  the  question  of  what  a  private  should  do  is  simple — he 
obeys  any  command  that  is  given.  It  is  when  out  of  ranks  that 
a  private  must  know  how  and  when  to  salute.  • 

SALUTING 

In  the  old  days  the  free  men  of  Europe  were  all  allowed  to 
carry  weapons,  and  when  they  met  each  would  hold  up  his  right 
hand  to  show  that  he  had  no  weapon  in  it,  and  that  they  met  as 
friends.  Slaves  or  serfs,  however,  were  not  allowed  to  carry 
weapons,  and  slunk  past  the  freeman  without  making  any  sign.  In 
this  way  the  salute  came  to  be  the  symbol  or  sign  by  which  soldiers 
(free  men)  might  recognize  each  other.  The  lower  classes  began 
to  imitate  the  soldiers  in  this  respect,  although  in  a  clumsy,  apol- 
ogetic way,  and  thus  there  crept  into  civil  life  the  custom  of  raising 
the  hand  or  nodding  as  one  passed  an  acquaintance.  The  soldiers, 
however,  kept  their  individual  salute,  and  purposely  made  it  intri- 
cate and  difficult  to  learn  in  order  that  it  cculd  be  acquired  only 

13 


14 


MILITARY  SIGNAL  CORPS  MANUAL 


by  the  constant  training  all  real  soldiers  received.  To  this  day 
armies  have  preserved  their  salute,  and  when  correctly  done  it  is 
at  once  recognized  and  never  mistaken  for  that  of  the  civilian. 
All  soldiers  should  be  careful  to  execute  the  salute  exactly  as  pre- 
scribed. The  civilian,  or  the  imitation  soldier,  who  tries  to  imitate 
the  military  salute,  invariably  makes  some  mistake  which  shows 
that  he  is  not  a  real  soldier ;  he  gives  it  in  an  apologetic  manner, 
he  fails  to  stand  or  march  at  attention,  his  blouse  is  unbuttoned 
or  hat  on  awry,  or  he  fails  to  look  the  person  saluted  in  the  eye. 
There  is  a  wide  difference  in  the  method  of  rendering  and  meaning 
between  the  civilian  salute  as  used  by  friends  in  passing,  or  by 
servants  to  their  employers,  and  the  military  salute,  the  symbol  and 
sign  of  the  military  profession. 

Enlisted  men  under  arms  or  with  their  hats  on  salute  all  officers 
of  United  States  and  foreign  armies.  Privates  do  not  salute  non- 
commissioned officers.  The  national  color  or  standard,  when  not 
cased  (i.  e.,  in  waterproof  cover),  is  saluted  by  all  officers  and 
men. 

To  salute  with  the  hand,  first  assume  the 
position  of  a  soldier  or  march  at  attention. 
Look  the  officer  you  are  to  salute  straight  in 
the  eye.  Then  when  the  proper  distance  sep- 
arates you  raise  the  right  hand  smartly  till 
the  tip  of  the  forefinger  touches  the  lower 
part  of  the  headdress  above  the  right  eye, 
thumb  and  fingers  extended  and  joined,  palm 
to  the  left,  forearm  inclined  at  about  45  de- 
grees, hand  and  wrist  straight.  Continue  to 
look  the  officer  you  are  saluting  straight  in 
the  eye,  and  keep  your  hand  in  the  position  of 
salute  until  the  officer  acknowledges  the  sa- 
lute or  until  he  has  passed.  Then  drop  the 
hand  smartly  to  the  side.  The  salute  is  given 
with  the  right  hand  only. 

Saluting  distance  is  that  within  which  rec- 
ognition of  rank  is  easy.  In  general  it  is 
about  30  paces.  In  approaching  or  passing 
within  saluting  distance,  individuals  or  bodies 
of  troops  exchange  salutes  when  at  a  distance 
of  about  6  paces.  If  they  do  not  approach 
each  other  that  closely,  the  salute  is  exchanged 
at  the  point  of  nearest  approach  within  sa- 
luting distance. 

Salute  the  national  color  or  standard  in  the  same  way  that  you 
would  an  officer.  (The  national  flag  belonging  to  dismounted  organ- 
izations is  called  a  color;  to  mounted  organizations,  a  standard.  1 


THE  SALUTE 


MILITARY  COURTESY  15 

Uncovering  is  not  a  form  of  the  prescribed  salute,  and  the  salute 
is  executed  only  when  covered.  Do  not  salute  when  marching  in 
double  time. 

Before  addressing  an  officer,  an  enlisted  man  makes  the  pre- 
scribed salute  with  the  rifle  if  he  is  armed  with  it,  or,  if  unarmed 
and  covered,  with  the  right  hand.  He  also  makes  the  same  salute 
after  receiving  a  reply.  If  uncovered  he  stands  at  attention  without 
saluting.  A  mounted  soldier  dismounts  before  addressing  an 
officer  not  mounted. 

A  noncommissioned  officer  or  private  in  command  of  a  detach- 
ment without  arms  salutes  all  officers  with  the  hand,  but  if  the 
detachment  is  armed  with  the  rifle  he  makes  the  rifle  salute.  If 
armed  with  the  saber  he  salutes  with  it. 

Indoors  an  unarmed  enlisted  man  uncovers  and  stands  at  atten- 
tion upon  the  approach  of  an  officer.  If  armed,  he  salutes  as  hereto- 
fore prescribed.  For  the  purpose  of  saluting,  the  drill  floor  of  an 
armory  is  considered  as  outdoors,  the  remainder  of  the  armory  as 
indoors. 

When  an  officer  enters  a  room  where  there  are  soldiers,  the  word 
"Attention"  is  given  by  some  one  who  perceives  him,  when  all  rise 
and  remain  standing  in  the  position  of  a  soldier,  until  the  officer 
leaves  the  room  or  commands  "Rest."  Soldiers  at  meals  do  not  rise 
but  cease  talking  and  eating. 

Soldiers  actually  at  work  or  engaged  in  athletic  exercises  do  not 
salute  unless  spoken  to.  Prisoners  are  not  permitted  to  salute ;  they 
merely  come  to  attention  if  not  actually  at  work. 

Officers  at  all  times  acknowledge  the  courtesies  of  enlisted  men 
by  returning,  in  the  manner  prescribed,  the  salutes  given.  When 
several  officers  in  company  are  saluted,  all  return  it. 

At  retreat,  when  the  "Star  Spangled  Banner"  is  played  by  the 
band,  or  "To  the  Color"  is  played  by  the  field  music,  while  the  flag 
is  being  lowered,  all  officers  and  enlisted  men  out  of  ranks  face  to- 
ward the  flag  (the  post  or  camp  flag),  stand  at  attention,  and  render 
the  prescribed  salute  at  the  last  note  of  the  music. 

Whenever  the  Star  Spangled  Banner  is  played  at  a  formal  occa 
sion  other  than  retreat  all  officers  and  enlisted  men  present  stand 
at  attention,  facing  toward  the  music,  retaining  that  position  until 
the  last  note  of  the  air,  and  then  salute.  The  playing  of  the  Star 
Spangled  Banner  as  a  part  of  a  medley  is  prohibited  in  the  military 
service. 

COURTESIES  IN  CONVERSATION 

In  speaking  to  an  officer,  always  stand  at  attention  and  use  the 
word  "Sir."  Examples : 

"Sir,  Private  Brown,  Company  B,  reports  as  orderly." 
"Sir.  the  first  sergeant  directed  me  to  report  to  the  captain." 


16  MILITARY  SIGNAL  COIN'S  MANUAL 

(Question  by  an  officer:)  "To  what  company  do  you  belong?" 

(Answer:)  ''Company  A,  sir." 

(Question  by  an  officer:)  "Has  first  call  for  drill  sounded?" 

(Answer:)  "No,  sir";  or  "Yes,  sir;  it  sounded  about  five  min- 
utes ago." 

(Question  by  an  officer:)  "Can  you  tell  me,  please,  where  Major 
Smith's  tent  is?" 

(Answer:)  "Yes,  sir;  I'll  take  you  to  it." 

Use  the  third  person  in  speaking  to  an  officer.    Examples : 

"Does  the  Lieutenant  wish,"  etc. 

"Did  the  Captain  send  for  me?" 

In  delivering  a  message  from  one  officer  to  another,  always  use 
the  form  similar  to  the  following:  "Lieutenant  A  presents  his  com- 
pliments to  Captain  B  and  states,"  etc.  This  form  is  not  used  when 
the  person  sending  or  receiving  the  message  is  a  private. 

In  all  official  conversation,  refer  to  other  soldiers  by  their  titles, 
thus :  Colonel  A,  Sergeant  B,  Private  C. 

Never  go  to  any  officer  to  make  a  request  or  complaint  without 
first  asking  permission  to  do  so  from  the  first  sergeant. 


RANK  AND   PRECEDENCE  OF  OFFICERS  AND   NON- 
COMMISSIONED  OFFICERS 

The  following  are  the  grades  of  rank  of  officers  and  noncommis- 
sioned officers : 

1.  Lieutenant  general. 

2.  Major  general. 

3.  Brigadier  general. 

4.  Colonel. 

5.  Lieutenant  colonel. 

6.  Major. 

7.  Captain. 

8.  First  lieutenant. 

9.  Second  lieutenant. 

10.  Veterinarian,     Cavalry,     and     Field  Artillery;     Pay     Clerk, 
Quartermaster  Corps. 

11.  Cadet. 

12.  (a)  Sergeant  major,  regimental;   sergeant   major,  senior 
grade  Coast  Artillery  Corps ;  (b)  master  electrician,  Quartermaster 
Corps  ;  master  electrician,  Coast  Artillery  Corps  ;  master  signal  elec- 
trician ;  chief  musician;  (c)  engineer,  Coast  Artillery  Corps. 

13.  (a)  Ordnance  sergeant ;  quartermaster  sergeant,  Quarter- 
master Corps;  sergeant,  first  class,  Hospital  Corps;  electrician  ser- 
geant,  first  class  Coast   Artillery  Corps;    (b)    sergeant,   first  class, 
Quartermaster  Corps ;  first-class  signal  sergeant. 


MI  LIT. IKY  COURTESY 


17 


14.  Quartermaster   sergeant   and   commissary   sergeant   regi- 
mental;   electrician    sergeant,    second    class,    Coast    Artillery 
Corps ;  master  gunner,  Coast  Artillery  Corps. 

15.  Sergeant  major,  squadron  and  battalion;  sergeant  major, 
junior  grade,  Coast  Artillery  Corps;  color  sergeant;  battalion  quar- 
termaster sergeant,  Engineers  and  Field  Artillery  Corps. 

16.  (a)  First  sergeant;  drum  major;  (b)  principal  musician; 
chief  trumpeter;  fireman.  Coast  Artillery  Corps. 

17.  Sergeant;     quartermaster     sergeant,     company;      stable 
sergeant. 

18.  Corporal. 

In  each  grade  and  subgrade,  date  of  commission,  appointment, 
or  warrant  determines  the  order  of  precedence. 

The  grade  of  noncommissioned  officers,  indicated  by  chevrons 
worn  on  the  sleeve,  and  the  insignia  of  rank  appearing  on  the 
shoulder  straps,  or  shoulder  loops  of  officers,  are  as  follows: 


SIGNAL  CORPS  CHEVRONS:  !— PRIVATE;  2— LANCE  CORPORAL; 
3— CORPORAL;  4— SERGEANT;  5— FIRST  CLASS  SERGEANT;  6— 
MASTER  SIGNAL  ELECTRICIAN. 

OFFICERS'  INSIGNIA:  7— FIRST  LIEUTENANT;  8— CAPTAIN;  9— MAJOR 
(Gold),  LIEUTENANT  COLONEL  (Silver);  10-COLONEL;  11— GEN- 
ERAL OFFICERS;  12— FIRST  LIEUTENANT,  CADETS;  13— CAPTAIN, 
CADETS;  14— MAJOR,  CADETS. 


18  MILITARY  SIGNAL  COA'/'.S"  MAXL'AL 

RULES   AND   REGULATIONS  OF   LAND  FORCES 

The  land  forces  of  the  United  States  consist  of  the  Regular 
Army,  the  Organized  Land  Militia  when  called  into  the  service 
of  the  United  States,  and  such  Volunteer  forces  as  Congress 
may  authorize. 

The  armies  of  the  United  States  are  governed  by  certain 
rules  and  regulations  called  "The  Articles  of  War." 

The  Militia  (National  Guard)  when  called  into  the  actual 
service  of  the  United  States  is  subject  to  the  same  rules  and 
articles  of  war  as  the  Regular  troops  of  the  United  States. 

When  not  in  the  actual  service  of  the  United  States,  the 
Militia  is  governed  by  such  rules  and  regulations  as  may  be 
prescribed  by  the  State  in  which  the  Militia  is  organized. 

The  control  of  the  Organized  Militia  when  not  in  the 
service  of  the  United  States,  which  is  vested  in  the  Federal 
Government,  through  constitutional  provisions  in  regard  to 
organization,  armament,  and  discipline  (training)  is  laid  down 
in  the  Regulations  of  the  War  Department  for  the  Organized 
Militia,  and  in  the  various  instruction  manuals. 

The  following  list  includes  the  offenses  most  often  commit- 
ted by  soldiers,  generally  through  ignorance  or  carelessness 
rather  than  viciousness.  Violations  of  any  rule  or  regulation 
should  be  carefully  guarded  against,  since  they  not  only  subject 
the  offender  to  punishment,  but  also  bring  discredit  on  his 
comrades,  his  organization,  and  on  the  military  profession. 

1.  Selling,  pawning,  or,  through   neglect,  losing  or   spoiling 
any  Government  property,  such   as   uniforms,  blankets,  equip- 
ment and  ammunition. 

2.  Disobedience   of   the   orders    of   any   officer   or   non-com- 
missioned officer. 

3.  Disrespect  to  an  officer  or  non-commissioned  officer. 

4.  Absence  from  camp  without  leave. 

5.  Absence  from  any  drill,  formation,  or  other  duty  without 
authority. 

6.  Noisy  or  disorderly  conduct  in  camp  or  when  absent  either 
with  or  without  leave. 

7.  Entering  on  private  property,  generally  for  the  purpose  of 
stealing  fruit  or  similar  errands. 

8.  Negligence    or   carelessness   at    drill   or   on    other   duty,   par- 
ticularly while  on  guard  or  as  a  sentinel  over  prisoners. 

9.  Wearing  an  unauthorized  uniform  or  wearing  the  uniform 
in  an  improper  manner. 

10.  Urinating  in  or  around  camp. 

11.  Failing  to  salute  properly. 

12.  Disrespect  or  affront  to  a  sentinel. 


MILITARY  COURTESY  19 

UNIFORMS 

Wear  the  exact  uniform  prescribed  by  your  commanding 
officer,  whether  you  are  on  duty  or  off  duty. 

Never  wear  a  mixed  uniform,  as,  for  instance,  a  part  of  the 
service  uniform  with  the  blue  uniform. 

Never  wear  any  part  of  the  uniform  with  civilian  clothes. 
It  is  very  unsoldierly,  for  example,  to  wear  a  civilian  overcoat 
over  the  uniform,  or  to  wear  the  uniform  overcoat  over  a 
civilian  suit. 

Keep  the  uniform  clean  and  neat  and  in  good  repair. 

Grease  spots  and  dust  and  dirt  should  be  removed  as  soon 
as  possible. 

Rips  and  tears  should  be  properly  mended. 

Missing  buttons  and  cap  and  collar  ornaments  should  be 
promptly  replaced. 

There  is  but  one  correct  and  soldierly  way  to  wear  the  cap. 
Never  wear  it  on  the  back  or  side  of  the  head. 

The  service  hat  should  be  worn  in  the  regulation  shape, 
peaked  with  four  indentations,  and  with  hat  cord  neatly  adjusted. 
Do  not  cover  it  with  pen  or  pencilmarks. 

Never  appear  outside  your  room  or  tent  with  your  blouse 
unbuttoned  or  collar  unhooked.  Chevrons,  service  stripes,  and 
campaign  medals  and  badges  are  a  part  of  the  uniform  and 
must  be  worn  as  prescribed. 

When  blouses  are  not  worn  with  the  service  uniform,  olive- 
drab  shirts  are  prescribed. 

Suspenders  must  never  be  worn  exposed  to  view. 

Never  appear  in  breeches  without  leggings. 

Leather  leggings  should  be  kept  polished.  Canvas  leggings 
should  be  scrubbed  when  dirty. 

Tan  (russet  leather)  shoes  should  be  kept  clean  and  pol- 
ished. 

The  overcoat  when  worn  must  be  buttoned  throughout  and 
the  collar  hooked.  When  the  belt  is  worn  it  is  worn  outside 
the  overcoat. 


PERSONNEL 

It  will  probably  be  conceded,  considering  the  duties  they  must 
perform,  that  the  men  who  make  up  the  Signal  Corps  should  be 
intelligent  and  well  instructed ;  furthermore,  that  both  officers  and 
men  should  remain  long  with  the  service  and  make  it  their  profes- 
sion. No  matter  how  efficient  may  be  the  instruments  and  equip- 
ment of  an  army,  no  matter  how  good  may  be  its  telegraph  lines,  its 
radio,  or  its  airplanes,  it  is  certain  that  their  value  will  depend 
almost  wholly  upon  the  men  who  use  them. 

In  the  United  States  the  transmission  of  military  information  is 
wisely  placed  in  charge  of  the  Signal  Corps  and  not  scattered  among 
several  branches  of  service.  The  advantage  of  this  concentration 
has  been  proved ;  and  it  is  not  perhaps  saying  too  much  in  claiming 
for  the  men  of  this  corps  as  high  a  standard  of  faithfulness,  indus- 
try, intelligence,  and  efficiency  as  exists  among  any  body  of 
soldiers  the  world  over.  The  enlisted  force  is  recruited  from 
intelligent  men  in  civil  life,  they  are  given  severe  training,  and  prac- 
tical instruction  as  telegraph,  telephone,  and  radio  men ;  as  auto- 
mobile drivers ;  in  telegraph  construction  and  maintenance ;  in  cable 
laying  and  testing ;  the  use  of  scientific  and  electrical  apparatus ;  in 
the  inflation  and  handling  of  balloons  and  scouting  and  reconnais- 
sance work  of  airplanes;  in  the  use  of  visual  methods  of  signaling; 
riding  and  the  care  of  horses  and  pack  animals  with  the  field  com- 
panies ;  in  fact,  in  the  almost  innumerable  duties  which  fall  to  their 
lot  in  service  with  their  corps.  The  theater  of  operations  is  widely 
extending;  the  march  of  military  service  is  rapidly  progressing; 
electricity  and  the  mechanical  arts  have  changed  the  very  face  of 
war;  and  so  a  technical  corps  such  as  is  the  Signal  Corps  must 
use  its  utmost  endeavor  to  keep  up  with  the  progress  of  ideas. 

It  has  been  said  that  recent  field  experiments  with  troops  have 
conclusively  proved  that  for  every  specially  trained  Signal  Corps 
soldier  provided,  not  only  is  the  field  information  service  many 
times  increased  in  efficiency,  but  that  at  least  two  men  are  returned 
to  the  firing  line  who  would  otherwise  be  removed  therefrom  to 
perform  the  inefficient  and  often  impossible  work  of  the  orderly 
of  the  past.  Since  this  messenger  service  must  be  provided,  either 

20 


SIGNAL  CORPS  PERSONNEL  21 

through  orderlies  or  trained  signal  troops,  it  is  manifest  that  the 
provision  of  a  minimum  per  cent  of  the  total  strength  for  this  pur- 
pose results  in  increasing  the  number  of  men  for  the  firing  line 
instead  of  taking  from  that  line. 

The  duties  of  a  corps  for  intelligence  communication  are  not, 
however,  confined  to  the  transmission  of  information  alone,  though 
that  is  its  principal  function.  For  in  addition  to  this  service  its 
troops  will  have  plenty  of  fighting  to  do,  not  only  with  the 
infantry  at  the  outposts  and  at  detached  stations,  but  with  the 
cavalry  in  reconnaissance  work,  and  with  both  when  serving 
with  contact  troops  and  with  patrols.  The  chief  duty  of  signal- 
men is,  of  course,  to  transmit  information  collected,  but  they 
are  by  no  means  to  remain  blind  and  deaf  to  the  events  taking  place 
around  them.  They  should  gather  all  the  information  possible  and 
transmit  it,  through  the  proper  channels,  to  headquarters,  as  is  the 
duty  of  all  soldiers.  Obviously,  while  signalmen  have  unusual 
opportunities  for  the  collection'  of  information  in  the  enemy's  coun- 
try, they  have  at  hand  the  means  of  transmission  as  well,  and  thus 
form  one  of  the  strongest  corps  of  observers  with  an  army.  Still 
it  is  not  to  be  forgotten  that  an  army  has  eyes  and  ears  everywhere, 
and  that  the  duty  of  obtaining  information  is  imposed  upon  all. 
The  chance  observation  of  a  sentinel,  a  report  from  an  outpost, 
the  story  of  a  prisoner  or  native  may  have  value  if  sent  in  time 
to  the  proper  authority.  This  is  the  first  duty  of  the  signalmen ; 
but  in  addition  signal  troops,  and  especially  the  aviators,  have 
become,  even  more  than  the  cavalry,  the  eyes  and  ears  of  the  army. 

The  need  for  training  and  experience  on  the  part  of  the  officers 
and  men  engaged  in  this  service  is  too  obvious  to  need  more 
than  a  mere  mention  and  it  will  be  sufficient  to  quote  here,  as 
an  indication  of  expert  opinion  on  this  subject,  the  following 
remarks  of  a  distinguished  French  officer: 

"Information  service  fails  especially  because  the  world  is 
ignorant  of  its  principles,  processes,  and  modes  of  action.  The 
transmission  of  intelligence  demands  special  organs.  Most  armies 
give  some  telegraphic  training  to  noncommissioned  officers  and 
troopers ;  it  is  lost  time.  Those  partly  informed  are  always  incom- 
petent ;  special-trained  men  are  necessary." 

This  brief  statement  might  be  well  considered  a  military  axiom 
to  be  placed  at  the  head  of  all  treatises  and  laws  affecting  the 
army. 


PROFICIENCY     TEST     FOR     COMPANIES     OF      SIGNAL 

TROOPS 

Companies  of  signal  troops  should  be  tested  technically  and 
administratively  from  time  to  time  by  specially  qualified  signal 
officers,  preferably  of  field  rank.  These  tests  act  as  stimu- 
lants to  the  work  of  the  companies  and  make  possible  a  very 
accurate  rating  of  them  as  regards  their  efficiency  in  the  per- 
formance of  field  duty. 

The  test  outlined  is"  prescribed  as  a  guide ;  suitable  varia- 
tions from  it  should  be  employed  if  necessity  therefor  arises. 

1.  Individual  tests  : 

(a)  Telegraphy   wire   or    radio.      Rating   as   to   ability    to    send 
and  receive   regular  messages   in   speed  of  words   per  minute. 
Office  practice.     Message  forms,  checks,  blanks,  and  rules  per- 
taining   to    telegraph    operation    and    the    handling    of    messages. 

(b)  Visual  signaling:  Wigwag — rate  per  minute  sending  and 
receiving  code.    Visual  signaling:  Semaphore — rate  per  minute 
sending  and  receiving  code. 

(c)  Lineman  (wire  and  outpost  companies) :  General  duties, 
tying,    splicing,    cutting   in.      Lineman    (telegraph    companies) : 
Details  of  semi-permanent  and  permanent  telegraph  and  tele- 
phone construction. 

(d)  Radio   operation    (radio   companies) :   Adjustments,   no- 
menclature, and  care  of  apparatus. 

(c)  Telephony  (outpost  and  telegraph  companies)  :  Tele- 
phones and  telephone  swichboards.  Operation,  adjustment. 
and  repairs. 

(/)  Motor  vehicles  (telegraph  companies) :  Operation,  ad- 
justment, and  repairs. 

(<?)  First  aid  and  personal  hygiene. 

(/i)  Care  of  arms  and  equipment. 

2.  Section  (platoon  outpost  companies)  test:  To  include  the 

22 


PKOFICIENCV   TEST   I' Oh'   COMPANIES  23 

handling  of  the  section  in  a  simple  practical  problem  calculated 
to  test  the  efficiency  of  the  section,  both  technically  and  in 
self-maintenance  in  the  field. 

3.  Company  test : 

(a)  Technical    inspection    (with    full    packs) :    Drill,    horse- 
manship,   marching,    camping,    inspection    of    arms    and    equip- 
ment. 

(b)  Administrative   inspection :    Condition   of   records,   mess 
administration,  stable  management. 

(c)  Field  problem :  An   advanced  problem  in  the   establish- 
ment of   lines   of   information   under  given   tactical  conditions. 
Organizations  as  a  whole  to  be  rated  as  to  methods  and  results. 

4.  Special   test :   Examination   of   specially  qualified  enlisted 
men. 

(a)  Heliograph:  Setting  up  and  adjustments.     Sending  and 
receiving. 

(b)  Acetylene  lantern  :  Setting  up  and  adjustments.    Sending 
and  receiving. 

(r)  Code  and  cipher:  Knowledge  and  use  of  cipher  disk. 


PART   II— DRILL   INSTRUCTION 

DRILL  REGULATIONS 

GENERAL  PRINCIPLES  AND  OBJECT  OK  INSTRUCTION 

The  certain  transmission  of  information  and  orders  from 
commanding  officers  to  their  subordinates  and  information  from 
subordinates  to  commanding  officers,  regardless  of  conditions  or 
terrain  (the  country  in  which  the  military  unit  is  operating),  is 
the  ultimate  object  of  all  training. 

The  special  qualifications  required  of  Signal  Corps  troops  in 
war  are  that  they  be  fully  equipped  with  efficient  men  and  ma- 
terial to  carry  out  the  orders  of  the  commanding  officer,  that 
they  are  able  to  maintain,  uninterruptedly,  such  communica- 
tions, either  by  electricity  or  visual  signaling,  or  both,  without 
regard  to  change  of  headquarters,  to  keep  the  commander  fully 
and  continuously  informed  as  to  the  progress  of  the  action,  the 
position  of  his  troops,  supply  trains  and  hospital  departments. 

To  meet  these  requirements,  the  Signal  Corps  must  have 
members  technically  trained  in  time  of  peace,  and  it  must  also 
be  prepared  to  cover  long  distances  quickly  and  to  overcome 
all  the  difficulties  and  obstacles  of  the  route,  and  still  keep  in 
touch  with  such  subordinate  commanders  as  orders  require. 

The  members  must  understand  thoroughly  all  classes  of 
signaling;  must  know  how  to  make  necessary  repairs  and  be 
prepared  to  meet,  tactically,  the  shifting  requirements  of  the 
battle  field  and  the  strategical  conditions  of  the  occupied  terri- 
tory. 

It  is  essential  that  mobility  be  acquired  through  thorough 
theoretical  training  and  extensive  practice  in  establishing  and 
maintaining  lines  of  information  over  varied  country  under 
conditions  approximating  those  of  service. 

The  instruction  is  designed  to  develop  resourcefulness,  in- 
itiative, and  self-reliance  for  Signal  Corps  men  of  all  grades. 
The  regulations  prescribe  the  method  of  training  in  the  or- 
dinary duties  of  field  companies  and  battalions  of  the  Signal 

24 


DRILL  REGULATIONS  25 

Corps,  and  all  soldiers  must  be  so  thoroughly  drilled  in  these 
duties  that  in  the  excitement  of  action  they  may  be  performed 
readily,  naturally,  and  as  a  matter  of  second  nature. 

Since  varied  conditions  arise  in  handling  Signal  Corps 
troops,  no  hard  and  fast  rules  can  be  laid  down  to  cover  all 
conditions ;  much  is  left  to  the  energy  and  ingenuity  of  the 
officers  and  non-commissioned  officers. 

Instruction  must  therefore  be  conducted  with  a  view,  first, 
to  drilling  the  personnel  thoroughly  in  their  habitual  duties; 
and  second,  to  afford  officers  and  men  practical  experience  in 
dealing  with  the  situations  and  difficulties  which  arise  in 
campaign. 

Solutions  of  practical  problems,  involving  at  first  simple 
tactical  situations  with  appropriate  units  should  be  required. 
This  instruction  should  be  progressive  and  include  the  use  of 
the  highest  tactical  unit  available.  Signal  troops  can  carry  out 
this  instruction  to  advantage  without  the  assistance  of  other 
troops,  but  it  is  always  desirable  that  field  conditions  be  dupli- 
cated, where  possible,  with  infantry,  cavalry  and  artillery  units. 

A  progressive  order  is  to  be  followed  in  all  instruction,  com- 
mencing with  theoretical  instruction  in  the  smallest  unit  and 
proceeding  to  the  larger  one,  culminating  in  field  maneuvers. 

Thorough  training  of  the  individual  soldier  is  the  basis  of 
efficiency.  Precision  and  attention  to  detail  are  required  in 
this  instruction,  for  from  it  the  soldier  must  acquire  that  habit 
of  implicit  obedience  to  orders,  and  of  accurate  performance 
of  his  individual  duties,  which  is  the  indispensable  requisite  for 
efficiency  in  combined  training.  Drills  should  be  frequent,  but 
short. 

Recruits  are  assembled  in  small  squads  for  the  beginning  of 
their  instruction.  As  the  instruction  progresses  it  may  be 
consistently  carried  on  by  sections,  platoons,  or  by  the  entire 
company.  This  principle  also  applies  to  technical  training,  par- 
ticularly to  visual  signaling,  telegraphy  and  telephony.  Group- 
ing according  to  progress  and  efficiency  should  be  strictly 
carried  out;  those  who  lack  aptitude  and  quickness  should  be 
placed  under  experienced  instructors. 

The  training  of  the  recruit  includes  instruction  in  the  duties 
of  sentinels,  the  care  of  equipment,  packing  of  field  kits,  tent 
pitching,  pistol  practice,  and  the  customs  and  courtesies  of  the 
service,  in  addition  to  his  training  as  a  signalman. 

The  instructor  of  each  unit  is  its  immediate  chiefs  and  should 
be  given  all  due  latitude  in  conducting  the  instruction,  and  be 
held  to  strict  accountability  for  results  attained.  The  habit 
of  self-reliance  and  a  feeling  of  responsibility  for  the  instruc- 


26  MILITARY  SIGNAL  CORPS  MANUAL 

tion  of  their  respective  units,  as  well  as  the  proper  feeling  of 
pride  in  these,  may  thus  be  developed  among  the  subordinate 
commanders. 

The  instructor  always  maintains  a  military  bearing,  and  by 
a  quiet,  firm  demeanor,  sets  a  proper  example  to  the  men. 
Faults  should  be  corrected  without  nagging. 

Instruction  in  establishing  wire,  wireless,  or  visual  lines  of 
information,  telegraphy,  and  tent  pitching  may  be  appropriate- 
ly given  by  section,  or  by  platoon,  as  a  healthy  rivalry  among 
the  units  may  thus  be  developed. 

Commanding  officers  are  accountable  for  the  proper  train- 
ing of  their  respective  organizations  within  the  limits  pre- 
scribed by  regulations  and  orders. 

The  excellence  of  an  organization  is  judged  by  its  field 
efficiency.  The  field  efficiency  of  an  organization  depends 
primarily  upon  its  effectiveness  as  a  whole.  Thoroughness  and 
uniformity  in  the  training  of  units  of  an  organization  are  in- 
dispensable to  the  efficiency  of  the  whole;  it  is  by  such  means 
alone  that  the  requisite  team  work  may  be  developed. 

The  drill  regulations  are  furnished  as  the  guide.  In  the  in- 
terpretation of  the  regulations,  the  spirit  must  be  sought. 
Quibbling  over  the  minutiae  of  form  is  indicative  of  failure  to 
grasp  the  spirit.  Drills  and  ceremonies  are  disciplinary  exer- 
cises designed  to  teach  precisive  soldiery  movements,  and  to 
inculcate  that  prompt  subconscious  obedience  which  is  essen- 
tial to  proper  military  control.  To  this  end,  smartness  and 
precision  should  be  exacted  in  the  execution  of  every  detail. 

GENERAL    RULES 

Movements  that  may  be  executed  toward  either  flank  are 
explained  as  toward  but  one  flank,  it  being  necessary  merely 
to  substitute  left  for  right,  or  the  reverse,  to  have  the  explana- 
tion of  the  corresponding  movement  toward  the  other  flank. 

Any  movement  may  be  executed  either  from  the  halt,  or 
when  marching,  unless  otherwise  prescribed. 

All  movements  on  foot  not  especially  excepted  may  be  exe- 
cuted in  double  time.  If  the  movement  be  from  the  halt,  or 
when  marching  in  quick  time,  the  command  double  time  pre- 
cedes the  command  march;  if  marching  in  double  time,  the 
command  double  time  is  omitted. 

In  successive  movements  executed  in  double  time  the  lead- 
ing or  base  unit  marches  in  quick  time  when  not  otherwise  pre- 
scribed;  the  other  units  march  in  double  time  to  their  places  in 
the  formation  ordered,  and  then  conform  to  the  gait  of  the 
leading  or  base  unit.  If  marching  in  double  time,  the  com- 


DRILL  REGULATIONS  27 

mand  double  time  is  omitted.  The  leading  or  base  unit  marches 
in  quick  time:  the  other  units  continue  at  double  time  to  their 
places  in  the  formation  ordered,  and  then  conform  to  the  gait  of 
the  leading  or  base  unit. 

To  hasten  the  execution  of  a  movement  begun  in  quick  time, 
the  command : 

1.  Double   time,  2.  MARCH 

is  given.  The  leading  or  base  unit  continues  to  march  at 
quick  time,  or  remains  at  halt  if  already  halted;  the  other 
units  complete  the  execution  of  the  movements  at  double  time 
and  then  conform  to  the  gait  of  the  leading  or  base  unit. 

If,  in  forming  elements  abreast  of  each  other,  the  command: 

1.  Company    (platoon,  etc.),  2.  HALT 

be  given  during  the  movements,  only  those  elements  halt  which 
have  reached  their  new  positions ;  the  others  continue  the  march 
and  halt  on  reaching  their  positions. 

For  the  purpose  of  correcting  errors  while  marching,  the 
instructor  may  command: 

1.  In  place,  2.  HALT 

when  all  halt  and  stand  fast.  To  resume  the  movement  the 
commands : 

1.  Resume,  2.  MARCH 
are  given. 

To  revoke  a  preparatory  command,  or  being  at  a  halt,  to  begin 
anew  a  movement  improperly  begun,  the  instructor  commands : 
AS  YOU  WERE,  at  which  the  movement  ceases  and  the  for- 
mer position  is  resumed. 

If  the  change  of  formation  requires  a  change  of  post  of 
officers  and  non-commissioned  officers,  they  proceed  by  the 
shortest  route  to.  their  posts  in  the  new  formation. 

While  the  posts  of  officers  and  non-commissioned  officers 
are  specified  as  instructors,  they  go  wherever  their  presence  is 
necessary. 

Officers  and  non-commissioned  officers  who  are  absent  are 
replaced  ordinarily  by  the  next  lower  rank.  In  a  company, 
chiefs  of  platoons  are  replaced  by  the  chiefs  of  sections  of  the 
platoons  in  the  order  of  rank.  Sergeants  and  corporals  replace 
absent  chiefs  of  sections. 

The  numerical  designation  of  units  does  not  change,  as  their 
relative  order  in  line  or  column  is  changed. 


28  MILITARY  SIGXAL  CORPS  MAKL'AL 

DEFINITIONS 

(Alphabetically    Arranged.) 

Alignment:  A  straight  line  upon  which  elements  are  formed, 
or  will  be  formed,  is  called  an  alignment.  The  act  of  dressing 
troops  on  a  straight  line  is  called  an  alignment. 

Base:     The  element  on  which  a  movement  is  regulated. 

Center:    The  middle  point,  or  element,  of  a  command. 

Column:  A  formation  with  the  elements  placed  one  behind 
another. 

Deploy:  To  extend  the  front.  To  exchange  from  column 
to  line,  or  close  order  to  extended  order. 

Depth:  The  space  from  head  to  rear  of  any  formation, 
including  the  leading  and  rear  elements. 

Distance:  The  space  between  elements  as  measured  from 
the  backs  of  men  in  front  to  breast  of  men  in  rear,  or  from  the 
croup  of  the  horse  in  front  to  the  head  of  the  horse  in  rear. 

Element:  Any  component  part  of  a  larger  unit,  a  file, 
squad,  platoon,  cart,  wagon,  section  or  company. 

File:  Two  men,  the  front-rank  man,  and  the  corresponding 
man  of  the  rear  rank.  The  front-rank  man  is  known  as  the 
file  leader.  The  term  file  also  applies  to  individual  men  in  a 
single-rank  formation.  When  a  file  has  no  rear-rank  man 
it  is  termed  a  blank  file. 

File  Closers:  The  officers  or  non-commissioned  officers  who 
are  posted  in  the  rear  of  the  line.  The  term  is  also  used, 
for  convenience,  to  designate  all  men  posted  in  the  line  of  file 
closers. 

Flank:  The  right  or  left  of  a  command  in  line  or  in  column: 
also  the  element  on  the  right  or  left  of  the  line. 


DRILL  DEFINITIOXS  29 

Formation:  Arrangement  of  the  element  of  a  command,  in 
their  order  in  line  or  in  column. 

Front:  The  space  in  width  occupied  by  an  element  in  line 
or  in  column. 

(The  front  of  a  man  is  figured  as  22  inches.) 

Guide:  A  soldier  upon  whom  the  element  regulates  its 
march. 

Head:     The  leading  element  of  a  column. 

Interval:  The  open  space  between  elements  abreast  of  each 
other,  or  on  the  same  line.  The  interval  between  men  in  ranks 
is  4  inches,  measured  from  elbow  to  elbow.  Between  squads, 
companies,  etc.,  it  is  measured  from  the  left  elbow  of  the  left 
man  or  guide  of  the  group  on  the  right,  to  the  right  elbow  of 
the  right  man  or  guide  of  the  group  on  the  left. 

Leap  frog:  A  method  of  maintaining  constant  communica- 
tion with  a  moving  command  by  using  two  or  more  instru- 
ments with  a  single  unit,  keeping  one  in  operation  while 
another  is  moving  past  it  to  a  position  in  front.  Commonly 
used  with  radio  sets  and  buzzer  instruments.  The  system 
may  be  used  in  dividing  up  the  construction  of  telegraph  lines. 

Left:     The'  left  extremity  or  element  of  a  body  of  troops. 

Line:  A  formation  in  which  the  different  elements  are 
abreast  of  each  other. 

Lines  of  Information:  Channels  along  which  military  infor- 
mation may  be  transmitted,  such  as  by  wire,  wireless,  visual 
signaling,  or  messenger. 

Maneuvers:  Operations  against  an  assumed,  outlined,  or 
actual  force  under  a  separate  commander,  who,  within  the 
limits  of  the  assumed  situation,  is  free  to  adopt  any  formations 
and  make  any  movement  he  chooses. 

Rank:     A  line  of  men  or  carts  abreast  of  each  other. 
Right:     The  right  extremity  or  element  of  a  body  of  troops. 


COMMANDS   AND    SIGNALS 

COMMANDS 

It  is  important  for  the  beginner  in  the  work  of  military  in- 
struction to  note  that  commands  are  of  two  kinds : 

The  preparatory  c"bmmand,  such  as  forward,  tells  the  move- 
ment that  is  to  be  executed. 

The  command  of  execution,  such  as  MARCH,  or  HALT  causes 
the  exexution  of  the  movement. 

Preparatory  commands  are  distinguished  in  type  by  bold 
face,  commands  of  execution  by  CAPITALS. 

When  the  preparatory  command  has  been  given,  an  interval 
of  time  is  allowed  sufficient  for  it  to  to  be  properly  understood 
before  the  command  of  execution  is  given.  The  tone  of  com- 
mand is  animated,  distinct,  and  sufficiently  loud  to  be  clearly 
heard  by  every  man  in  the  ranks.  Indifference  in  giving  com- 
mands leads  to  laxity  in  execution;  each  preparatory  command 
should  be  pronounced  with  a  rising  inflection  of  voice,  in  such 
manner  that  the  command  of  execution  may  be  more  energetic 
and  elevated. 

The  command  of  execution  is  firm  in  tone  and  brief. 

When  giving  commands  to  troops  it  is  usually  best  to  face 
them. 

ARM    SIGNALS 

Commands  are  given  by  the  officer  in  charge  of  the  squad, 
platoon,  or  company,  as  the  case  may  be.  In  company  form- 
ation commands  given  verbally  by  the  captain  may  be  supple- 
mented by  trumpet  or  bugle  signals,  or  by  signals  made  by  the 
arm.  A  short  blast  of  the  whistle  is  sometimes  used  on  the 
march  or  in  combat  to  fix  the  attention  of  troops,  their  com- 
manders or  leaders,  preparatory  to  giving  commands,  orders,  or 
signals.  These  supplementary  signals  are  primarily  designed 
to  facilitate  the  movement  of  mounted  troops,  but  their  value  in 

30 


COMMANDS  AND  SIGNALS  31 

battle  is  at  once  obvious  and  knowledge  of  their  meaning  and 
execution  should  be  possessed  by  every  man  in  the  signal  service 
who  desires  to  be  prepared  for  any  emergency. 

Commands  given  by  the  captain  are  repeated  by  chiefs  of 
platoons,  or  appropriate  commands  are  given  to  their  platoons 
in  time  to  insure  the  proper  execution  of  the  movement.  The 
chiefs  of  platoons  ordinarily  give  their  commands  verbally, 
supplemented,  if  necessary,  by  the  appropriate  arm  signal. 
Chiefs  of  sections  repeat  the  commands  in  the  same  manner. 

Arm  signals  are  ordinarily  made  with  the  right  arm,  but  may 
be  made  with  the  left  arm  when  convenient. 

The  arm  signals  illustrated  and  described  are  regulation  with 
the  U.  S.  Army  Signal  Corps,  mounted.  The  infantry  arm 
signals  are  slightly  different  in  character  and  must  not  be  con- 
fused when  observing  the  maneuvers  of  companies  of  infantry. 
Only  the  preparatory  signals  are  shown;  for  the  signal  of 
execution  the  arm  is  extended  vertically  and  then  lowered 
quickly  to  the  side  in  every  case. 

PREPARATORY  SIGNALS 

Attention.— Extend  the  arm  vertically  and  move  it  slowly 
back  and  forth  from  right  to  left. 

Forward.— Extend  the  arm  vertically  and  lower  it  to  the 
front  until  horizontal. 

By  the  right  (left)  flank.— Extend  the  arm  vertically  anc 
lower  it  to  the  right  (left)  until  horizontal. 

Right  (left)  about.— Extend  the  arm  vertically  and  describ 
slowly  a  large  horizontal  circle  with  the  hand;  then  extend  the 
arm  to  the  left  (right)  and  describe  a  horizontal  arc  to  front 
and  right  (left). 

Right  (left)  oblique.— Extend  the  arm  obliquely  upward 
the  right  (left)  and  front,  and  then  lower  the  arm,  describing  a 
vertical  circle  on  the  right  (left)  side  of  the  horse. 

To  increase  the  gait.— Carry  the  hand  to  the  shoulder,  fore- 
arm vertical;  extend  the  arm  vertically  from  this  position  and 
repeat  several  times. 

To  decrease  the  gait.— Hold  the  arm  horizontally  above  am 
in  front  of  the  forehead. 

To  indicate  an  increased  or  decreased  gait  for  a  maneuver, 
the  appropriate  signal  is  made  just  after  the  preparatory  signal 
for  the  maneuver. 

To  halt.— Extend  the  arm  vertically  and  hold  i 
the  signal  is  obeyed. 

To  change  direction  to  the  right  (left).-Extend  the  arm 
vertically;  lower  it  to  the  left  (right)  until  horizontal  and  de- 
scribe a  horizontal  arc  to  the  front  and  right  (left). 


32  MILITARY  SIGX.1L  CORPS  .V./AT./L 

Right  (left)  by  section. — Point  at  the  right  (left)  section 
and  signal  forward. 

Right  (left)  front  into  line. — Extend  the  arm  vertically  and 
describe  several  large  vertical  circles  on  the  right  (left)  side 
of  the  horse. 

BUGLE    CALLS 

Bugle  or  trumpet  calls  fall  into  the  following  classifications: 

Warning  calls. 

Formation  calls. 

Alarm  calls. 

Service  calls. 

Drill  signals  are  also  included  for  mounted  troops. 
WARNING    CALLS 

First  call  and  guard  mounting  precede  the  assembly  by  such 
intervals  as  may  be  prescribed  by  the  commanding  officer. 

Mess,  church  and  fatigue,  though  classed  as  service  calls, 
may  be  used  as  warning  calls. 

First  call  is  the  signal  for  formation  dismounted;  it  does 
not  precede,  and  is  not  used  in  connection  with  other  warning 
calls. 

Guard  mounting  is  the  first  signal  for  guard  mounting. 

Call  to  quarters  is  the  signal  for  men  to  repair  to  their 
quarters. 

FORMATION    CALLS 

Assembly  is  the  signal  for  companies  or  details  to  fall  in. 

Adjutant's  call  is  the  signal  for  companies  to  form  battalion ; 
also  for  the  guard  details  to  form  for  guard  mounting  on  the 
parade  ground;  it  follows  the  assembly  at  such  interval  as  may 
be  prescribed  by  the  commanding  officer. 

To  the  standard  is  sounded  when  the  standard  salutes. 

ALARM    CALLS 

Fire  call  is  the  signal  for  falling  in,  without  arms,  to  ex- 
tinguish fire. 

To  arms  is  the  signal  for  falling  in,  under  arms,  as  quickly 
as  possible. 

SERVICE    CALLS 

Tatoo,  taps,  mess,  sick,  church,  recall,  officers  ,  captains  ,  first 
sergeants,  fatigue,  school  and  the  general  are  service  calls. 

The  general  is  the  signal  for  striking  tents  and  loading 
wagons  preparatory  to  marching. 

Reveille  precedes  the  assembly  for  roll  call;  retreat  follows 
the  assembly;  the  interval  being  only  that  required  for  forma- 
tion and  roll  call  except  when  there  is  a  parade. 

Taps  is  the  signal  for  extinguishing  lights;  it  is  usually  pre- 
ceded by  call  to  quarters. 


BUGLE   CALLS 


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SCHOOL  OF  THE  SOLDIER 

GENERAL  PROVISIONS 

This  instruction  has  for  its  object  the  training1  of  the  in- 
dividual recruit,  and  afterwards  the  squad.  It  must  be  given 
with  the  greatest  attention  to  detail. 

The  instructor  explains  briefly  each  movement,  firs+  exe- 
cuting it  himself,  if  practicable.  He  requires  the  recruits  to 
take  the  positions  unassisted  and  does  not  touch  them  for  the 
purpose  of  correcting  faults,  except  when  they  are  unable  to 
correct  themselves.  He  avoids  keeping  them  too  long  at  the 
same  movement,  although  each  should  be  understood  before 
passing  to  another ;  by  degrees  the  desired  precision  and  uni- 
formity is  exacted. 

In  the  instruction  of  the  recruit,  frequent  short  rests  are 
given  in  order  that  the  men  may  not  be  unduly  fatigued. 

The  instructor  takes  advantage  of  these  rests  to  instruct  the 
recruits  in  the  customs  and  courtesies  of  the  service,  the  duties 
of  orderlies,  the  proper  manner  of  receiving  messages  from  and 
delivering  them  to  officers,  etc.,  so  that  when  the  recruit  finally 
reports  for  duty  he  will  not  only  know  his  prescribed  drill 
thoroughly,  but  will  know  how  to  conduct  himself  as  a  trained 
soldier. 

From  the  beginning,  the  instructor  insists  on  a  smart  ap- 
pearance and  requires  that  clothing  be  clean  and  neatly 
adjusted. 

For  the  individual  instruction,  a  few  recruits,  usually  not  ex- 
ceeding four,  are  placed  in  single  rank,  about  4  inches  apart. 

They  execute  the  marchings  as  explained  for  the  squad. 

POSITION   OF  THE   SOLDIER,   OR   ATTENTION 

Heels  on  the  same  line  and  as  near  each  other  as  the  con- 
formation of  the  man  permits. 

45 


46 


MILITARY  SIGNAL  CORJ'S  MANUAL 


RECRUIT    INSTRUCTION,    ILLUSTRATING    THE    POSITION    OF 
THE   SOLDIER 

Feet  turned  out  equally  and  forming  an  angle  of  about  45 
degrees. 

Knees  straight  without  stiffness. 

Hips  level  and  drawn  back  slightly:  body  erect  and  resting 
equally  on  hips;  chest  lifted  and  arched;  shoulders  square  and 
falling  equally. 

Arms  and  hands  hanging  naturally,  thumb  along  the  seam 
of  the  trousers. 

Head  erect  and  squarely  to  the  front,  chin  drawn  in  so  that 
the  axis  of  the  head  and  neck  is  vertical;  eyes  straight  to  the 
front. 

Weight  of  the  body  resting  equally  upon  the  heels  and  balls 
of  the  feet. 


To    ASSEMBLE 

To  teach  the  recruits  to  assemble,  the  instructor  first  places 
them  in  a  single  rank  arranged  according  to  height,  the  tallest 
man  on  the  right ;  intervals  of  4  inches  are  maintained  between 
men,  as  nearly  as  practicable.  The  objects  of  the  interval,  it  is 
explained,  are  to  give  freedom  of  movement  in  marching.  Re- 
cruits are  directed  to  open  out  the  right  elbow  slightly  until 
the  left  elbow  of  the  man  on  the  right  is  lightly  touched;  the 
elbow  is  then  withdrawn.  This  is  repeated  several  times  and 
the  recruits  are  then  instructed  to  fall  out  and  the  man  on  the 


SCHOOL  OF  THE  SOLDIER  47 

right  being  placed  in  position,  they  are  instructed  that  at  the 
command,  FALL  IN,  they  successively  and  quickly  take  their 
places  in  rank  as  before. 

THE   RESTS 

Being  at  a  halt,  the  commands  are  FALL  OUT;  REST;  AT 
EASE;  and,  1.  Parade,  2.  REST. 

At  the  command  fall  out,  the  men  may  leave  the  ranks, 
but  are  required  to  remain  in  the  immediate  vicinity.  They 
resume  their  former  places,  at  attention,  at  the  command 
fall  in. 

At  the  command  rest  each  man  keeps  one  foot  in  place, 
but  is  not  required  to  preserve  silence  or  immobility. 

At  the  command  at  case  each  man  keeps  one  foot  in 
place  and  is  required  to  preserve  silence  but  not  immobility. 

1.  Parade,  2.  REST.  Carry  the  right  foot  6  inches  straight 
to  the  rear,  left  knee  slightly  bent;  clasp  the  hands,  without 
constraint,  in  front  of  the  center  of  the  body,  fingers  joined, 
left  hand  uppermost,  left  thumb  clasped  by  the  thumb  and  fore- 
finger of  the  right  hand;  preserve  silence  and  steadiness  of 
position. 

To  resume  the  attention :     1.  Squad,  2.  ATTENTION. 

The  men  take  the  position  of  the  soldier. 

EYES  RIGHT  OR  LEFT 

1.  Eyes,  2.  RIGHT  (LEFT),  3.  FRONT. 

At  the  command  right,  turn  the  head  to  the  right  oblique, 
eyes  fixed  on  the  line  of  eyes  of  the  men  in,  or  supposed  to  be 
in,  the  same  rank.  At  the  command  front,  turn  the  head  and 
eyes  to  the  front. 

FACINGS 

To  the  flank:  1.  Right  (left),  2.  FACE. 

Raise  slightly  the  left  heel  and  right  toe;  face  to  the  right, 
turning  on  the  right  heel,  assisted  by  a  slight  pressure  on  the 
ball  of  the  left  foot ;  place  the  left  foot  by  the  side  of  the  right. 
Left  face  is  executed  on  the  left  heel  in  the  corresponding 
manner. 

Right  (left)  half  face  is  executed  similarly,  facing  45  degrees. 

To  face  in  inarching  and  advance,  turn  on  the  ball  of  either 
foot  and  step  off  with  the  other  foot  in  the  new  line  of  direc- 
tion ;  to  face  in  marching  without  gaining  ground  in  the  new 
direction,  turn  on  the  ball  of  either  foot  and  mark  time. 


48  MILITARY  SIGNAL  CORPS  MANUAL 

To  the  rear:     1.  About,  2.  FACE. 

Carry  the  toe  of  the  right  foot  about  half  foot-length  to 
the  rear  and  slightly  to  the  left  of  the  left  heel,  without  chang- 
ing the  position  of  the  left  foot ;  face  to  the  rear,  turning  to 
the  right  on  the  left  heel  and  right  toe;  place  the  right  heel  by 
the  side  of  the  left. 

SALUTE  WITH  THE  HAND 

1.  Hand,  2.  SALUTE. 

Raise  the  right  hand  smartly  until  the  tip  of  the  forefinger 
touches  the  lower  part  of  the  headdress  (if  uncovered,  the  fore- 
head) above  the  right  eye,  thumb  and  fingers  extended  and 
joined,  palm  to  the  left,  forearm  inclined  at  about  45  degrees, 
hand  and  wrist  straight;  at  the  same  time  look  toward  the 
person  saluted  (two).  Drop  the  arm  smartly  by  the  side. 

For  rules  governing  salutes,  see  "Military  Courtesy." 

STEPS  AND  MARCHINGS 

With  the  exception  of  right  step,  all  steps  in  marching  exe- 
cuted from  a  halt  begin  with  the  left  foot. 

The  length  of  the  full  stop  in  quick  time  is  30  inches,  meas- 
ured from  heel  to  heel,  and  the  cadence  is  at  the  rate  of  120 
steps  per  minute. 

The  length  of  the  full  step  in  double  time  is  36  inches ;  the 
cadence  is  at  the  rate  of  180  steps  per  minute. 

The  instructor,  when  necessary,  indicates  the  cadence  of  the 
step  by  calling  one,  two,  three,  four,  or  left,  right,  the  instant 
the  left  and  right  foot,  respectively,  should  be  planted. 

The  arms  hang  naturally,  the  hands  moving  about  6  inches 
to  the  front  and  3  inches  to  the  rear  of  the  seam  of  the  trousers. 

All  steps  and  marchings  and  movements  involving  march 
are  executed  in  quick  time  unless  the  squad  be  marching  in 
double  time,  or  double  time  be  added  to  the  command ;  in  the 
latter  case  double  time  is  added  to  the  preparatory  command. 
Example:  1.  Squad  right,  double  time,  2.  MARCH  (School  of 
the  squad). 

QUICK  TIME 

Being  at  a  halt,  to  march  forward  in  quick  time  :  1.  For- 
ward, 2.  MARCH. 

At  the  command  march,  move  the  left  foot  smartly 
the  right  leg,  left  knee  straight. 

At  the  command  march,  move  the  left  foot  smartly 
straight  forward  30  inches  from  the  right,  sole  near  the  ground, 


SCHOOL   OF  THE  SOLDIER  49 

and  planted  without  shock;  next,  in  like  manner,  advance  the 
right  foot  and  plant  it  as  described;  continue  to  march.  The 
arms  swing  naturally. 

DOUBLE    TIME 

Being  at  a  halt,  or  in  marching  in  quick  time,  to  march  in 
double  time :  1.  Double  time,  2.  MARCH. 

If  at  a  halt,  at  the  first  command  shift  the  weight  of  the  body 

to  the  right  leg.  At  the  command  march,  raise  the  forearms, 
fingers  closed,  to  a  horizontal  position  along  the  waist  line, 
take  up  an  easy  run  with  a  step  at  the  cadence  of  double  time 
(180  steps  per  minute)  allowing  a  natural  swinging  motion  to 
the  arms. 

If  marching  in  quick  time,  at  the  command  march,  given 
as  either  foot  strikes  the  ground,  take  one  step  in  quick  time, 
and  then  step  off  in  double  time. 

To  resume  the  quick  time :     1.  Quick  time,  2.  MARCH. 

At  the  command  march,  given  as  either  foot  strikes  the 
ground,  advance  and  plant  the  other  foot  in  double  time;  re- 
sume the  quick  time,  dropping  the  hands  by  the  sides. 

To  MARK  TIME 

Being  in  march  :  1.  Mark  time,  2t  MARCH.  At  the  com- 
mand march,  given  as  either  foot  strikes  the  ground,  advance 
and  plant  the  other  foot ;  bring  up  the  foot  in  rear  and  continue 
the  cadence  by  alternately  raising  each  foot  about  2  inches 
and  planting  it  on  a  line  with  the  other. 

Being  at  a  halt,  at  the  command  march,  raise  and  plant  the 
feet  as  described  above. 

THE  HALF  STEP 

1.  Half  step,  2.  MARCH. 

Take  steps  of  IS  inches  in  quick  time,  18  inches  in  double 
time. 

Forward,  half  step,  halt,  and  mark  time,  may  be  executed 
one  from  the  other  in  quick  or  double  time. 

To  resume  the  full,  step  from  half  step  or  mark  time :  1. 
Forward,  2.  MARCH. 

SIDE    STEP 

Being  at  a  halt  or  mark  time:  1.  Right  (left)  step,  2. 
MARCH. 

Carry  and  plant  the  right  foot  15  inches  to  the  right  having 
the  left  foot  beside  it  and  continue  the  movement  in  the 
cadence  of  quick  time. 


50  MILITARY  SIGNAL  CORPS  MANUAL 

The  side  step  is  used  for  short  distances  only  and  is  not 
executed  in  double  time. 

BACK    STEP 

Being  at  a  halt  or  mark  time:     1.  Backward,  2.  MARCH. 
Take  steps  of  15  inches  straight  to  the  rear. 
The  back  step  is  used  for  short  distances  only  and  is  not 
executed  in  double  time. 

To    HALT 

To  arrest  the  march  in  quick  or  double  time:  1.  Squad,  2. 
HALT. 

At  the  command  halt,  given  as  either  foot  strikes  the 
ground,  plant  the  other  foot  as  in  marching;  raise  and  place 
the  first  foot  by  the  side  of  the  other.  If  in  double  time,  drop 
the  hands  by  the  sides. 

To  MARCH   BY  THE  FLANK 

Being  in  march  :    1.  By  the  right  (left)  flank,  2.  MARCH. 

At  the  command  march,  given  as  the  right  foot  strikes  the 
ground,  advance  and  plant  the  left  foot,  then  face  to  the  right 
in  marching  and  step  off  in  the  new  direction  with  the  right 
foot. 

To  MARCH  TO  THE  REAR 

Being  in  march  :  1.  To  the  rear;  2.  MARCH. 

The  command  march,  given  as  the  right  foot  strikes  the 
ground,  advance  and  plant  the  left  foot;  turn  to  the  right 
about  on  the  balls  of  both  feet  and  immediately  step  off  with 
the  left  foot. 

If  marching  in  double  time,  turn  to  the  right  about,  taking 
four  steps  in  place,  keeping  the  cadence,  and  then  step  off  with 
the  left  foot. 

CHANGE    STEP 

Being  in  march  :    1.  Change  step,  2.  MARCH. 

At  the  command  march,  given  as  the  right  foot  strikes 
the  ground,  advance  and  plant  the  left  foot;  plant  the  toe  of 
the  right  foot  near  the  heel  of  the  left  and  step  off  with  the  left 
foot. 

The  change  on  the  right  foot  is  similarly  executed,  the  com- 
mand march  being  given  as  the  left  foot  strikes  the  ground. 


SCHOOL   OF   THE  SOLDIER  51 

COVERING  AND  MARCHING  ON   POINTS 

The  instructor  indicates  two  points  and  requires  that  re- 
cruits, in  succession,  place  themselves  upon  the  prolongation 
of  a  straight  line  through  these  points  and  then  to  march  upon 
them  both  in  quick  and  double  time. 

It  is  demonstrated  to  the  recruits  that  they  cannot  march  in 
a  straight  line  without  selecting  two  points  in  the  desired  direc- 
tion and  keeping  them  covered  while  advancing. 

A  distant  and  conspicuous  landmark  is  next  selected  as  the 
point  of  direction.  The  recruit  is  required  to  choose  two  inter- 
mediate points  in  line  with  the  point  of  direction  and  march 
upon  it  by  covering  these  points,  new  points  being  selected  as 
he  advances. 


PHYSICAL  TRAINING 

In  the  employment  of  the  various  forms  of  physical  training 
it  is  necessary  that  well  defined  methods  should  be  introduced 
so  that  the  object  of  the  training  may  be  attained  in  a  sys- 
tematic manner.  In  planning  these  methods  the  following  fac- 
tors must  be  considered:  (a)  the  condition  and  physical  apti- 
tude of  the  members,  (b)  facilities,  (c)  time,  (d)  instruction 
material. 

The  question  of  physical  aptitude  is  a  very  important  one 
and  should  always  determine  the  nature  and  extent  of  the  task 
expected  of  the  members.  It  is  advisable  to  divide  the  members 
into  three  classes :  (a)  the  recruit  class,  (b)  the  intefmediate 
class,  (c)  the  advanced  class,  planning  the  work  for  each  pro- 
gressively. 

Time  is  a  decidely  important  factor  and  no  plan  can  be 
made  unless  those  in  charge  of  this  work  know  exactly  how 
much  time  they  have  at  their  disposal.  Experience  has  proven 
that  in  citizen-soldier  units  a  15  minute  drill  in  setting  up  ex- 
ercises is  sufficient  on  drill  nights. 

The  proper  use  of  the  instruction  material  is  undoubtedly 
the  most  important  point  of  an  instructor's  duty.  Every  exer- 
cise has  a  function  peculiarly  its  own;  it  has  a  certain  effect 
upon  a  certain  part  of  the  body.  So  far  as  possible,  every  les- 
son should  be  planned  to  embrace  setting-up  exercises  that  call 
into  action  all  parts  of  the  body.  It  is  also  advisable  that  a 
movement  requiring  a  considerable  amount  of  muscular  exer- 
tion should  be  followed  by  one  in  which  this  exertion  is  re- 
duced to  a  minimum.  One  portion  of  the  body  should  not  be 
exercised  successively,  that  is,  arm  exercises  should  be  followed 
by  a  trunk  exercise,  and  that  in  turn  by  a  leg,  shoulder,  and 
neck  exercise. 

The  work  laid  down  here  should  not  be  followed  blindly; 
every  instructor  should  select  such  portions  as  in  his  opinion 
are  productive  of  the  best  results  under  the  conditions,  and  if 
necessary  vary  them  in  accordance  with  changing  conditions. 

52 


PHYSICAL   TRAINING  53 

Short  and  frequent  drills  should  be  given  in  preference  to 
long  ones,  which  are  liable  to  exhaust  all  concerned,  and  ex- 
haustion means  lack  of  interest  and  benefit.  All  movements 
should  be  carefully  explained,  and,  if  necessary,  illustrated  by 
the  instructor. 

The  lesson  should  begin  with  the  less  violent  exercises, 
gradually  working  up  to  those  that  are  more  so,  then  gradu- 
ally working  back  to  the  simple  ones,  so  that  the  men  at  the 
close  of  the  drill  will  be  in  as  nearly  a  normal  condition  as  pos- 
sible. Everything  in  connection  with  physical  training  should  be 
planned  so  that  the  men  look  forward  to  it  with  pleasure.  Never 
exercise  men  to  the  point  of  exhaustion.  If  there  is  evi- 
dence of  panting,  faintness,  fatigue,  or  pain,  the  exercise  should 
be  stopped  at  once. 

SETTING   UP   EXERCISES 

The  commands  are  of  two  kinds :  the  preparatory,  indicating 
the  movement  to  be  executed,  and  the  command  of  execution, 
causing  the  execution.  The  continuation  of  an  exercise  is  car- 
ried out  by  repeating  the  command,  which  usually  takes  the 
form  of  numerals,  the  numbers  depending  upon  the  number 
of  movements  that  an  exercise  comprises.  Thus,  if  an  exer- 
cise consists  of  two  movements,  the  counts  will  be  1,2;  or  if  it 
consists  of  eight  movements,  the  counts  will  be  correspondingly 
increased. 

In  the  continuation  of  an  exercise  the  preparatory  command 
is  explanatory,  the  command  of  execution  causes  the  execution 
and  the  continuation  is  caused  by  a  repetition  of  numerals  de- 
noting the  number  of  movements  required,  or  of  words  de- 
scribing the  movements  if  words  are  used. 

Each  command  must  indicate,  by  its  tone,  how  that  par- 
ticular movement  is  to  be  executed ;  thus,  if  an  exercise  con- 
sists of  two  movements,  one  of  which  is  to  be  energized,  the 
command  corresponding  to  that  movement  must  be  empha- 
sized. 

Many  of  the  arm  exercises  are  short  and  snappy;  hence 
the  command  should  be  given  in  a  smart  tone  of  voice,  and 
the  interval  between  the  commands  should  be  short. 

The  leg  exercises  cannot  be  executed  as  quickly  as  those  of 
the  arms ;  therefore,  the  commands  should  be  slightly  drawn  out 
and  follow  one  another  in  slow  succession. 

The  trunk  exercises,  owing  to  the  deliberateness  of  execu- 
tion should  be  considerably  drawn  out  and  follow  one  another 
in  slow  succession. 

All  commands  should  be  given  in  a  clear  and  distinct  tone 
of  voice  and  an  effort  should  be  made  in  this  tone  to  inspire 


54 


MILITARY  SIGNAL  CQRPS  MANUAL 


the  men  with  enthusiasm  so  that  they  will  execute  the  exer- 
cises with  willingness,  snap  and  precision. 

Blouses  should  be  unbuttoned  and  the  cap  removed. 

FORMATIONS 

The  men  form  in  a  single  or  double  rank,  the  tallest  man 
on  the  right. 

Instructor  commands  :     1.  Count  off. 

At  this  command,  all  except  the  right  file  execute  "eyes 
right"  and  beginning  on  the  right,  the  men  in  each  rank  count 
1,  2,  3,  4;  each  man  turning  his  head  and  eyes  to  the  front  as  he 
counts. 

The  instructor  then  commands :  1.  Take  distance,  2.  MARCH, 
3.  Squad,  4.  HALT. 

At  the  command  "march,"  number  1  of  the  first  rank  moves 
straight  to  the  front;  numbers  2,  3,  and  4  of  the  front  and 
numbers  1,  2,  3,  and  4  of  the  rear  rank,  in  the  order  named, 
move  straight  to  the  front,  each  stepping  off  so  as  to  follow 
the  preceding  man  at  four  paces  ;  the  command  "halt"  is  given 
when  all  have  their  distances. 

In  nearly  all  the  arm  exercises  it  is  necessary  to  hold  the 
arms  in  some  fixed  position  from  which  the  exercises  can  be 
most  advantageously  executed,  and  to  which  position  the  arms 
are  again  returned  upon  completing  the  exercise.  These  po- 
sitions are  termed  "starting  positions";  and  though  it  may  not 
he  absolutely  necessary  to  assume  one  of  them  before  or  dur- 


STARTING  POSITIONS,  FROM  WHICH  EXERCISES  ARE  EXECUTED 


PHYSICAL   TRAINING  55 

ing  the  employment  of  any  other  portion  of  the  body,  it  is 
advisable  to  do  so,  since  they  give  to  the  exercise  a  finished, 
uniform  and  graceful  appearance. 

Intervals  having  been  taken  and  attention  assumed,  the  in- 
structor commands : 

1.  Arms  forward,  2.  RAISE,  3.  Arms,  4.  DOWN  (Fig.  1). 

At  the  command  raise,  raise  the  arms  to  the  front  smartly, 
extended  to  their  full  length,  till  the  hands  are  in  front  of  and 
at  the  height  of  the  shoulders,  palms  down,  fingers  extended 
and  joined,  thumbs  under  forefingers.  At  Arms,  DOWN,  resume 
position  of  attention. 

1.  Arms  sideward,  2.  RAISE,  3.  Arms,  4.  DOWN.  (Fig.  2). 

At  the  command  raise,  raise  the  arms  laterally,  until  hori- 
zontal, palms  down,  fingers  as  in  1. 

The  arms  are  brought  down  smartly  without  allowing  them 
to  touch  the  body. 

1.  Arms  upward,  2.  RAISE,  3.  Arms,  4.  DOWN  (Fig.  3). 

At  the  command,  raise,  raise  the  arms  from  the  sides,  ex- 
tended to  their  full  length,  with  the  forward  movement,  until 
they  are  vertically  overhead,  backs  of  hands  turned  outward, 
fingers  as  in  1. 

This  position  may  also  be  assumed  by  raising  the  arms 
laterally  until  vertical.  The  instructor  cautions  which  way  he 
desires  it  done. 

1.  Arms  backward,  2.  CROSS,  3.  Arms,  4.  DOWN.     (Fig.  4). 

At  the  command  cross,  the  arms  are  folded  across  the  back; 
hands  grasping  forearms. 

1.  Arms  to  thrust,  2.  RAISE,  3.  Arms,  4.  DOWN.     (Fig.  5). 

At  the  command  raise,  raise  the  forearms  to  the  front  until 
horizontal,  elbow  forced  back,  upper  arms  against  the  chest, 
hands  tightly  closed,  knuckles  down. 

1.  Hands  on  hips,  2.  PLACE,  3.  Arms,  4  DOWN.  (Fig.  6). 

At  the  command  place,  place  the  hands  on  the  hips,  the 
finger  tips  in  line  with  trouser  seams;  fingers  extended  and 
joined,  thumbs  to  the  rear,  elbows  pressed  back. 

1.  Hands  on  shoulders,  2.  PLACE,  3.  Arms,  4.  DOWN.  (Fig.  7). 

At  the  command  place,  raise  the  forearms  to  the  vertical 
position,  palms  inward,  without  moving  the  upper  arms;  then 
raise  the  elbows  upward  and  outward  until  the  upper  arms  are 
horizontal:  at  the  same  time  bending  the  wrist  and  allowing 
the  finger  tips  to  rest  lightly  on  the  shoulders. 

1.    Fingers    in    rear    of    head,   2.    LACE,   3.    Arms,   4.    DOWN. 

(Fig.  8). 


56 


Fig.  3 


Fig.  4 


Fig.  5 


PHYSICAL  TRAINING 


57 


At  the  command  lace,  raise  the  arms  and  forearms  as  de- 
scribed in  7,  and  lace  the  fingers  behind  the  lower  portion  of  the 
head,  elbows  well  up  and  pressed  well  back. 

These  positions  should  be  practiced  frequently,  and  instead 


Fig.  6 


Fig.  7 


Fig.  8 


of  recovering  the  position  of  attention  after  each  position,  the 
instructor  may  change  directly  from  one  to  another  by  giving 
the  proper  commands  instead  of  commanding  Arms,  DOWN. 

These  changes  should,  however,  be  made  only  after  the  po- 
sitions are  thoroughly  understood  and  correctly  assumed. 


58  MILITARY  SIGNAL  CORPS  MANUAL 


RECRUIT  INSTRUCTION 

First  Scries 

In  these  lessons  only  the  preparatory  command  is  given 
here.  The  command  of  execution,  which  is  invariably  Exercise, 
and  the  commands  of  continuance,  as  well  as  the  command  to 
discontinue,  having  been  already  explained,  are  omitted. 

Position  of  attention,  from  at  ease  and  rest. 

Starting  position,  Figs.  1  to  8. 

Raise  and  lower  arms  to  side  horizontal. 

Two  counts;  repeat  8  to  10  times,  Fig.  2. 

The  arms  rigidly  extended  are  brought  to  the  sides  smartly 
without  coming  in  contact  with  the  thighs.  Inhale  on  first  and 
exhale  on  second  count. 

1.  Hands  on  hips,  2.  PLACE,  3.  QUARTER  BEND  TRUNK 
FORWARD. 

Two  counts ;  repeat  8  to  10  times,  Fig.  9. 

The  trunk  is  inclined  forward  at  the  waist  about  45  deg.  and 
then  extended  again ;  the  hips  are  as  perpendicular  as  possible ; 
execute  slowly;  exhale  on  first  and  inhale  and  raise  chest  on 
second  count. 

1.  Arms  to  thrust,  2.  RAISE,  3.  RAISE  SHOULDERS. 

Two  counts;  repeat  8  to  10  times,  Fig.  10. 

The  shoulders  are  raised  as  high  as  possible  without  de- 
ranging the  position  of  the  body  or  head  and  lowered  back  to 
position;  execute  briskly;  inhale  on  first  and  exhale  on  sec- 
ond count. 

1.  Hands  on  hips,  2.  PLACE,  3.  QUARTER  BEND  KNEES. 

Two  counts;  repeat  8  to  10  times,  Fig.  11. 

The  knees  are  flexed  until  the  point  of  the  knee  is  directly 
over  the  toes;  whole  foot  remains  on  ground;  heels  closed; 
head  and  body  erect;  execute  moderately  fast,  emphasizing  the 
extension;  breathe  naturally. 

1.  Arms  backward,  2.  CROSS,  3.  RISE  ON  TOES. 

Two  counts;  repeat  8  to  10  times.  Fig.  12. 

The  body  is  raised  smartly  until  the  toes  and  ankles  are 
extended  as  much  as  possible;  heels  closed;  head  and  trunk 
erect;  in  recovering  position  heels  are  lowered  gently;  breathe 
naturally. 


PHYSICAL   TRAINING 


59 


Fig.  9 


Fig.  10 


Fig.    11  Fig.    12 

1.  Breathing  exercise;  2.  INHALE,  3.  EXHALE. 

At  inhale  the  arms  are  stretched  forward  overhead  and  the 
lungs  are  inflated;  at  exhale  the  arms  are  lowered  laterally  and 
the  lungs  deflated;  execute  slowly;  repeat  four  times. 


60  MILITARY  SIGNAL  CORPS  MANUAL 


Second  Series 

Position  of  attention,  as  in  first  series. 
Repeat  first  lesson. 

1.  Hands  on  shoulders,  2.  PLACE,  3.  EXTEND  ARMS  FOR- 
WARD. 

Two  counts ;  repeat  8  to  10  times. 

The  arms  are  extended  forward  forcibly,  palms  down,  and 
brought  back  to  position  smartly,  elbows  being  forced  back; 
exhale  on  first  and  inhale  on  second  count. 

1.  Hands  on  hips,  2.  PLACE,  3.  BEND  TRUNK  BACK- 
WARD. 

Two  counts;  repeat  6  to  8  times.  Fig  13. 

The  trunk  is  bent  backward  as  far  as  possible;  head  and 
shoulders  fixed;  knees  extended;  feet  firmly  on  the  ground; 
hips  as  nearly  perpendicular  as  possible;  in  recovering  care 
should  be  taken  not  to  sway  forward;  execute  slowly;  inhale 
on  first  and  exhale  on  second  count. 

I.  Arms  to  thrust,  2.  RAISE,  3.  MOVE  SHOULDERS  FOR- 
WARD. 

Two  counts ;  repeat  8  to  10  times,  Fig.  14. 

The  shoulders  are  relaxed  and  moved  forward  and  in  as 
far  as  possible  and  then  moved  backward  without  jerking; 
head  and  trunk  erect;  execute  slowly;  exhale  on  first  and  in- 
hale on  second  count. 

1.  Arms  backward,  2.  CROSS,  3.  HALF  BEND  KNEES. 

Two  counts ;  repeat  8  to  10  times,  Fig.  15. 

The  knees  are  separated  and  bent  halfway  to  the  ground, 
point  of  knee  being  forced  downward ;  head  and  trunk  erect ; 
execute  smartly  and  emphasize  the  extension;  breathe  natur- 
ally. 

1.  Hands  on  hips,  2.  PLACE,  3.  HALF  BEND  TRUNK  FOR- 
WARD. 

Two  counts ;  repeat  8  to  10  times,  Fig.  16. 

The  trunk  is  inclined  forward  until  it  is  at  right  angles  to 
the  legs,  hips  perpendicular;  knees  extended;  head  and  shoul- 
ders fixed;  execute  moderately  slow;  exhale  on  first  and  inhale 
and  raise  chest  on  second  count. 


61 


Fig.  13 


Fig.  14 


Fig.  15 


Fig.  16 


1.  Hands  on  shoulders,  2.  PLACE,  3.  STRIKE  ARMS  SIDE- 
WARD. 

The  arms,  knuckles  down,  hands  closed  are  flung  outward 
forcibly  and  brought  back  to  shoulders  smartly;  execute  fast, 
breathe  naturally. 

Breathing  exercise. 


62  MILITARY  SIGNAL  CORPS  MANUAL 


Third  Series 

Position  of  attention. 

Repeat  sejcond  lesson. 

Raise  arnis "overhead  laterally. 

Two  counts ;'  repeat  8  to  10  times,  Fig.  3. 

The  arms,  rigidly  extended  at  the  elbows,  are  raised  over- 
head, palms  inward,  smartly  and  brought  down  the  same  way ; 
execute  moderately  fast;  inhale  on  the  first  and  exhale  on  the 
second  count. 

1.  Hands  on  hips.  2.  PLACE,  3.  BEND  TRUNK  SIDEWARD, 
RIGHT  OR  LEFT. 

Two  counts;  repeat  6  to  8  times,  Fig.  17. 

The  trunk,  stretched  at  the  waist,  is  inclined  sideward  as 
far  as  possible,  head  and  shoulders  fixed;  knees  extended  and 
feet  firmly  on  the  ground;  execute  slowly;  inhale  on  first  and 
exhale  on  second  count.* 

1.  Arms  to  thrust,  2.  RAISE,  3.  BEND  HEAD  FORWARD 
AND  BACKWARD. 

Four  counts ;  repeat  6  to  8  times,  Fig.  18. 

The  chin  is  drawn  in  and  the  head  bent  forward,  back 
muscTes  of  neck  being  stretched  upward;  shoulders  remain 
fixed;  in  recovering  the  muscles  are  relaxed;  execute  slowly; 
inhale  and  raise  chest  on  first  and  exhale  on  second  count. 
In  bending  the  head  backward  the  muscles  of  the  neck  are 
stretched  upward;  breathe  as  before. 

Curl  shoulders  forward. 

Two  counts  ;  repeat  6  to  8  times,  Fig.  19. 

The  shoulders  relaxed  are  rolled  forward  as  far  as  possi- 
ble;  arms  being  rotated  forward;  they  are  then  rolled  back- 
ward and  the  arms  are  rotated  backward;  execute  slowly;  ex- 
hale on  first  Snd  inhale  on  second  count. 

1.  Hands  on  hips,  2.  PLACE,  3.  FULL  BEND  KNEES. 

Two  counts;  repeat  6  to  8  times,  Fig.  20. 

The  knees  are  separated  and  bent  as  much  as  possible; 
point  of  knees  forced  forward  and  downward;  heels  together; 
trunk  and  head  erect;  execute  slowly;  breathe  naturally. 


PHYSICAL   TRAINING 


63 


1.  Hands  in  rear  of  head,  2.  LACE,  3.  On  toes,  4.  RISE.  5. 
ROCK. 

Two  counts,  repeat  6  to  8  times. 

The  body  is  raised  on  toes  and  then  by  short  and  quick  ex- 
tensions and  flexions  of  the  toes  it  is  lowered  and  raised, 
knees  extended;  heels  together  and  free  from  the  ground; 
breathe  naturally. 

Breathing  exercise  as  in  first  lesson. 


Fig.   17 


Fig.    18 


Fig.    19 


Fig.  20 


64  MILITARY  SIGNAL  CORPS  MANUAL 

Fourth  Series 
Repeat  third  series. 

1.  Arms  to  thrust,  2.  RAISE,  3.  THRUST  ARMS  FOR- 
WARD. 

Two  counts;  repeat  8  to  10  times,  Fig.  21. 

The  arms,  knuckles  up,  are  thrust  forward  forcibly;  in  re- 
covering the  elbows  are  forced  back;  execute  moderately  fast; 
exhale  on  first  and  inhale  on  the  second  count. 

I.  Hands  on  shoulders,  2.  PLACE,  3.  TWIST  TRUNK  SIDE- 
WARD, RIGHT  OR  LEFT. 

Two  counts ;  repeat  6  to  8  times,  Fig.  22. 

The  trunk  is  turned  to  the  right  or  left  as  far  as  possible; 
hips  as  nearly  perpendicular  as  possible;  shoulders  square  and 
head  erect;  knees  extended  and  feet  firm;  execute  slowly;  in- 
hale on  first  and  exhale  on  second  count. 

1.  Arms  to  thrust,  2.  RAISE,  3  TURN  HEAD  RIGHT,  OR 
LEFT. 

Two  counts ;  repeat  6  to  10  times,  Fig.  23. 

The  head,  chin  square,  is  turned  to  the  right,  or  left  as  far 
as  possible,  muscles  of  the  neck  being  stretched;  shoulders  re- 
main square;  execute  slowly;  breathe  naturally. 

1.  Hands  on -hips,  2.  PLACE,  3.  RAISE  KNEE. 

Two  counts ;  repeat  10  to  12  times,  Fig.  24. 

The  thigh  and  knee  are  flexed  until  they  are  at  right  angles, 
thigh  horizontal;  toes  depressed;  the  right  knee  is  raised  at 
one  and  the  left  at  two;  trunk  and  head  erect ;  execute  in 
cadence  of  quick  time ;  breathe  naturally. 

1.  Fingers  in  rear  of  head,  2.  LACE,  3.  FULL  BEND  TRUNK 
FORWARD. 

Two  counts ;  repeat  6  to  8  times,  Fig.  25. 

The  trunk  is  bent  forward  as  far  as  possible;  knees  ex- 
tended; feet  firm;  head  and  shoulders  fixed;  execute  slowly; 
exhale  on  first  and  inhale  on  second  count. 

1.  Hands  on  hips,  2.  PLACE,  3.  On  toes,  4.  RAISE,  5.  HOP. 

Two  counts ;  repeat  12  to  16  times. 

The  body  is   raised  on   toes   and  the  hopping  is  performed 
with  knees   extended;   execute   fast;   breathe   naturally 
Breathing  exercise. 


PHYSICAL   TRAINING 


65 


Fig.  21 


Fig.  22 


Fig.  23 


Fig.  24 


Fig.  25 


66  MILITARY  SIGNAL  CORPS  MANUAL 

Fifth  Series 
Repeat  fourth  series. 

1.  Arms  forward,  2.  RAISE,  3.  STRETCH  ARMS  SIDE- 
WARD. 

Two  counts;  repeat  6  to  8  times,  Fig.  26. 

From  the  front  horizontal  the  arms  are  extended  to  their 
fullest  extent  and  then  stretched  sideward,  the  arms  rotating 
till  the  palms  are  up;  the  sideward  movement  is  performed 
slowly;  the  recovery  relaxed  and  quick;  inhale  on  first  and 
exhale  on  the  second  count. 

1.  Hands  on  hips,  2.  PLACE,  3.  BEND  TRUNK  OBLIQUELY 
FORWARD,  RIGHT  OR  LEFT. 

Two  counts ;  repeat  4  to  8  times,  Fig.  27. 

The  trunk  is  turned  to  the  right  and  bent  forward  to  the 
half-bend  position ;  shoulders  remain  square,  in  the  plane  of  the 
ground;  head  fixed;  knees  straight;  feet  firm;  hips  as  nearly 
perpendicular  as  possible;  execute  slowly;  exhale  on  the  first 
and  inhale  and  raise  chest  on  second  count. 

1.  Arms  to  thrust,  2.  RAISE,  3.  EXTEND  LEG  FORWARD. 

Two  counts ;  repeat  8  to  10  times,  Fig.  28. 

The  knee  and  ankle  are  extended  forward  with  a  snap,  the 
toes  just  escaping  the  ground;  all  extensor  muscles  contracted; 
in  recovering  relax;  trunk  and  head  erect;  execute  briskly; 
breathe  naturally. 

1.  Hands  on  shoulders,  2.  PLACE,  3.  MOVE  ELBOWS  FOR- 
WARD. 

Two  counts ;  repeat  8  to  10  times,  Fig.  29. 

The  elbows  are  brought  together  horizontally  in  front  and 
then  forced  back  as  far  as  possible;  the  forward  movement 
relaxed,  the  backward  a  stretch  not  a  jerk;  execute  moder- 
ately fast;  exhale  on  the  first  and  inhale  on  the  second  count. 

1.  Hands  on  hips,  2.  PLACE,  3.  BEND  TRUNK  FORWARD 
AND  BACKWARD. 

Two   counts,   repeat  6  to  8   times. 

Bend  trunk  forward  to  the  half-bend  position,  Fig.  16,  and 
then  backward,  Fig.  13;  execute  slowly;  exhale  on  first  and 
inhale  on  second  count. 


PHYSICAL   TRAINING 


67 


1.  Arms  backward,  2.  CROSS,  3.  RAISE  ON  TOES,  RIGHT 
AND  LEFT  ALTERNATELY. 

Four  counts ;   repeat  10  to   12  times,  Fig.  30. 

The  body  is  extended  on  the  toes  of  the  right  foot  and 
then  on  those  of  the  left;  heels  closed;  trunk  and  head  erect; 
execute  moderately  fast;  breathe  naturally 

Breathing  exercise. 


Fig.  26 


Fig.  27 


Fig.  28 


Fig.  29 


Fig.  30 


68  MILITARY  SIGNAL  CORPS  MANUAL 

Sixth  Series 
Repeat  fifth  series. 

1.  Arms  forwarded  overhead,  2.  RAISE,  3.  SWING  ARMS 
DOWNWARD  AND  UPWARD. 

Two  counts ;  repeat  8  to   10  times,  Fig.  31. 

1.  Arms  sideward  overhead,  2.  RAISE,  3.  Fingers,  4.  LACE, 
5.  BEND  TRUNK  SIDEWARD,  RIGHT  AND  LEFT. 

Two   counts ;   repeat   6   to   8   times,   Fig.   32, 
The   arms   are   fully   extended   and   the   body,   stretched   at 
the    waist,    is    bent    sideward    to    the    right    and    left;    knees 
straight;  feet  firm;  head  erect;  execute  slowly;  breathe  natur- 
ally. 

1.  Knees  to  squatting  position,  hands  on  hips,  2.  BEND, 
3.  ROCK. 

Two  counts ;  repeat  6  to  8  times. 

The  knees  are  bent  as  in  Fig.  20;  extend  and  bend  the 
knees  in  quick  succession;  trunk  and  head  erect;  heels  closed; 
execute  moderately  fast ;  breathe  naturally. 

1.  Arms  to  thrust,  2.  RAISE,  3.  MOVE  SHOULDERS  FOR- 
WARD,  UP,  BACK  AND  DOWN. 

Four  counts ;  repeat  8  to  10  times. 

The  shoulders  are  relaxed  and  brought  forward;  in  that 
position  they  are  raised;  then  they  are  forced  back  without 
lowering  them;  and  then  they  are  dropped  back  to  position; 
execute  slowly;  exhale  on  the  first,  inhale  on  the  second 
and  third  and  exhale  on  the  last  count. 

1.  Arms  to  thrust,  2.  RAISE,  3.  THRUST  ARMS  FOR- 
WARD;  SWING  THEM  SIDEWARD,  FORWARD,  AND 
BACK  TO  POSITION. 

Four  counts;  repeat  8  to  10  times. 

The  arms  are  thrust  forward,  then  relaxed  and  swung 
sideward,  then  forward  and  finally  brought  back  to  position, 
pressing  elbows  well  to  the  rear ;  execute  moderately  fast ; 
exhale  on  the  first  and  third  and  inhale  on  the  second  and 
fourth  counts. 


69 


I.  HOP  TO  SIDE  STRADDLE  AND  SWING  ARMS  OVER 
HEAD  LATERALLY  AND  RECOVER  POSITION  OF  ATTEN- 
TION. 

Two  counts ;  repeat  8  to  10  times,  Fig.  33. 

The  distance  between  the  legs  is  about  30  inches  ;  in  alight- 
ing the  toes  come  in  contact  with  the  ground  first  and  knees 
are  bent  slightly;  trunk  and  head  erect;  arms  extended; 
execute  moderately  fast ;  breathe  naturally. 

Breathing  exercises. 


Fig.  31 


Pig.  32 


Fig.  33 


SCHOOL     OF     THE  SQUAD 

THE   SQUAD 

As  soon  as  the  recruits  are  sufficiently  instructed  for  the 
purpose,  they  are  formed  into  squads  of  convenient  size  in 
order  to  teach  them  the  principles  of  the  alignments,  taking 
intervals,  and  the  marchings. 

For  this  instruction,  the  recruits  are  formed  in  double  rank. 
The  files  on  the  right  and  left  of  the  squad  are  always  com- 
plete;  if  there  be  an  incomplete  file,  it  will  be  second  from  the 
left.  The  rear-rank  men  cover  their  file  leaders  accurately  at 
1  yard  distance. 

In*  the  case  of  a  small  number  of  recruits,  they  may  be 
formed  in  single  rank.  The  movements  described  for  the  double 
rank  formation  apply  equally  well  to  the  single  rank,  omitting 
the  explanations  for  the  rear-rank  men. 

To  FORM  THE  SQUAD 

To  form  the  squad,  the  instructor  designates  a  recruit  as 
the  front-rank  man  of  the  right  file  and  indicates  to  him  where 
the  right  of  the  squad  is  to  rest;  he  then  places  himself  about  3 
yards  in  front  of  where  the  center  is  to  be  formed,  and  com- 
mands: FALL  IN. 

The  men  form  on  the  designated  recruit,  in  two  ranks  facing 
to  the  front,  as  already  prescribed. 

The  rear  rank  forms  with  distance  of  40  inches. 

The  instructor  then  commands  :  COUNT  OFF. 

At  this  command,  all  except  the  right  file  execute  eyes  right, 
and  beginning  on  the  right,  the  men  in  each  rank  count  one,  two, 
three,  four;  each  man  turns  his  head  and  eyes  to  the  front  as  he 
counts. 

The  squad  executes  the  rests;  resumes  the  attention;  marks 
time ;  and  executes  the  facinys.  the  setting-up  exercises,  the  steps, 

70 


SCHOOL  OF   THE  SQUAD  71 

and  the  halt,  and  is  dismissed  by  the  same  commands  and  means  as 
explained  for  the  recruit. 

ALIGNMENTS 

The  alignments  are  first  taught  by  requiring  the  recruits  to 
align  themselves  upon  two  files  established  as  a  base. 

Being  at  a  halt,  the  instructor  causes  the  first  two  files  on 
the  flank  toward  which  the  alignment  is  to  be  made  to  move 
forward  a  few  paces,  and  establishes  them  as  a  base;  he  then 
commands  :  1.  Right  (left),  2.  DRESS,  3.  FRONT. 

At  the  command  dress,  all  men  place  the  left  hand  upon 
the  hip  (whether  dressing  to  the  right  or  left);  each  man, 
except  the  base  file,  when  on  or  near  the  new  line  executes 
eyes  right,  and,  taking  steps  of  2  or  3  inches,  places  himself  so 
that  his  right  arm  rests  lightly  against  the  arm  of  the  man  on 
his  right,  and  so  that  his  eyes  and  shoulders  are  in  line  with 
those  of  the  men  on  his  right ;  the  rear  rank  men  cover  in  file. 

The  instructor  verifies  the  alignment  of  both  ranks  from 
the  right  flank  and  orders  up  or  back  such  men  as  may  be  in 
rear,  or  in  advance,  of  the  line;  only  the  men  designated  move. 

At  the  command  front,  given  when  the  ranks  are  aligned, 
each  man  turns  his  head  and  eyes  to  the  front  and  drops  his 
left  hand  by  his  side. 

In  the  first  drills  the  basis  of  the  alignment  is  established  on, 
or  parallel  to,  the  front  of  the  squad;  afterwards,  in  oblique 
directions. 

Whenever  the  position  of  the  base  file  or  files  necessitates 
a  considerable  movement  by  the  squad,  such  movement  will  be 
executed  by  marching  to  the  front  or  oblique,  to  the  flank  or 
backward,  as  the  case  may  be,  without  other  command. 

To  preserve  the  alignment  when  marching:  GUIDE  RIGHT 
(LEFT).  . 

The  men  preserve  their  intervals  from  the  side  of  the  guide, 
yielding  to  pressure  from  that  side  and  resisting  pressure  from 
the  opposite  direction  ;  they  recover  intervals,  if  lost,  by  gradu- 
ally opening  out  or  closing  in ;  they  recover  alignment  by 
slightly  lengthening  or  shortening  the  step;  the  rear-r.ank  men 
cover  their  file  leaders  at  40  inches. 

In  double  rank,  the  front-rank  man  on  the  right,  or  desig- 
nated flank,  conducts  the  march  ;  when  marching  faced  to  the 
flank,  the  leading  man  of  the  front  rank  is  the  guide. 

To  TAKE  INTERVALS 

Being  in  line  at  a  halt:  1.  Take  interval,  2.  To  the  right 
(left),  3.  MARCH.  4.  Squad,  5.  HALT. 


72 


MILITARY  SIGNAL  CORPS  MANUAL 


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ILLUSTRATION    OF   THE   MOVEMENT,    "TAKE    INTERVAL' 
"ASSEMBLE"— READ    DOWN    COLUMNS 


AND 


At  the  first  command,  the  rear  rank  steps  back  4  steps  and 
halts ;  at  the  command  march,  all  face  to  the  right  and  the  lead- 
ing man  of  each  rank  steps  off ;  the  other  men  step  off  in 
succession  so  as  to  follow  the  preceding  man  at  4  paces,  rear 
rank  men  marching  abreast  of  their  file  leaders. 

At  the  command  halt,  given  when  all  have  their  intervals, 
all  halt  and  face  to  the  front. 

To   ASSEMBLE 

1.  Assemble,  to  the  right  (left),  2.  MARCH. 

The  front-rank  man  on  the  right  stands  fast,  the  rear-rank 
man  on  the  right  closes  to  40  inches.  The  other  men  face  to  the 
right,  close  by  the  shortest  line,  and  face  to  the  front. 

MARCHINGS 

During  the  marchings  the  guide  conducts  the  march,  pre- 
serving with  great  care  the  direction,  length,  and  cadence  of 
the  step  and  selecting  points  on  which  to  march 


To  MARCH  TO  THE  FRONT 

Being  at  a  halt :     1.  Forward,  2.  MARCH. 

The  men  step  off  and  march  straight  to  the  front. 

If  in  line,  the  rear-rank  men  follow  their  file  leaders  ac- 
curately. The  instructor  sees  that  the  ranks  preserve  the 
alignment  and  the  intervals  toward  the  side  of  the  guide, 


SCHOOL  OF  THE  SQUAD  73 

The  men  yield  to  pressure  from  that  side  and  resist  pressure 
from  the  opposite  side;  by  slightly  shortening  or  lengthening 
the  step  they  gradually  recover  the  alignment,  and  by  slightly 
opening  out  or  closing  in  they  gradually  recover  the  interval, 
if  lost ;  while  habitually  keeping  the  head  to  the  front,  they 
may  occasionally  glance  toward  the  side  of  the  guide  to  as- 
sure themselves  of  the  alignment  and  interval,  but  the  head  is 
turned  as  little  as  possible  for  this  purpose. 

If  in  flank  column,  the  men  of  the  leading  file  step  off  at 
full  step;  the  leading  rear-rank  man  marches  abreast  of  his 
file  leader  at  26  inches  interval.  The  other  files  march  at  the 
half  step,  each  taking  the  full  step  when  at  1  yard  distance. 

Being  in  march :     1.  To  the  rear,  2.  MARCH. 

Executed  as  explained  in  preceding  chapter,  "School  of  the 
Soldier,"  paragraph  :  To  March  to  the  Rear. 

If  at  a  halt,  the  squad  may  be  faced  about  and  then  moved 
forward,  as  explained  in  the  preceding  paragraph;  or,  without 
facing  about,  it  may  be  marched  a  short  distance  to  the  rear, 
by  the  command :  1.  Backward,  2.  MARCH. 

Whenever  the  squad  in  line  is  faced  about  or  marched  to 
the  rear,  all  men  in  the  front  rank  not  covered  step  into  the 
new  front  rank. 


To  MARCH  BY  THE  FLANK 

Being  in  line  :    1.  By  the  right  (left)  flank,  2.  MARCH. 

At  the  second  command,  given  as  the  right  foot  strikes 
the  ground,  advance  and  plant  the  left  foot,  then  face  to  the 
right  in  marching  and  step  off  in  the  new  direction  with  the 
right  foot.  The  rear-rank  men  cover  accurately. 

The  formation  obtained  by  marching  by  the  flank  from  line 
is  called  a  flank  column. 

If  at  a  halt,  the  squad  may  be  marched  by  the  flank  by  first 
facing  it  in  the  desired  direction  and  then  moving  it  forward,  as 
explained  in  "To  March  to  the  Front." 

When  the  march  by  the  flank  is  executed  from  flank  column 
while  at  1  yard  distance,  the  files  close  in  gradually  toward  the 
guide  until  they  have  the  prescribed  interval. 

Whenever  the  flank  column  is  halted  while  marching  at  1 
yard  distance,  the  leading  file  halts  at  the  command;  the  others 
close  to  facing  distance  before  halting. 

To  close  up  the  flank  column  without  halting:  1.  Close,  2. 
MARCH. 

The  leading  file  takes  the  half  step;  the  other  files  close 
to  facing  distance  and  take  the  half  step;  all  the  files  having 


74 


MILITARY  SIGNAL  CORPS  MAX  UAL 


closed  to  facing  distance,  the  column  is  halted  or  marched  by 
the  flank  as  previously  explained. 

To  halt  the  flank  column  without  closing  up  :  1.  In  place;  2. 
HALT. 

To  MARCH  OBLIQUELY 

For  the  instruction  of  recruits,  the  squad  being  correctly 
aligned,  the  instructor  causes  the  squad  to  face  half  right  or 
half  left,  points  out  to  the  men  their  relative  positions  and 
explains  that  these  are  to  be  maintained  in  the  oblique  march. 

1.  Right  (left)  oblique,  2.  MARCH. 

Each  man  steps  off  in  a  direction  45  degrees  to  the  right  of 
his  former  front.  He  preserves  his  relative  position,  keeping 
his  shoulders  parallel  to  those  of  the  guide  (the  man  on  the 
right  front  of  the  line  or  column),  and  so  regulates  his  step 
as  to  keep  the  ranks  parallel  to  their  original  direction. 

If  the  command  halt  be  given  while  marching  obliquely, 
the  men  halt  faced  to  the  original  front. 

To  resume  the  original  direction  :  1.  Forward,  2.  MARCH, 
3.  Guide  right  (or  left). 

At  half  step  or  mark'  time,  while  obliquing,  the  oblique  march 
is  resumed  by  the  commands  :  1.  Oblique,  2.  MARCH. 


-ana- 


ILLUSTRATION  OF  SQUAD  TURNING 
ON  MOVING   PIVOT 

TO    CHANGE    DIRECTION    IN    FLANK   COLUMN 
TURN  ON  MOVING  PIVOT 

1.  Right  (left)  turn,  2.  MARCH. 

The  movement  is  executed  by  each  rank  successively  and  on 
the  same  ground.  At  the  second  command,  the  pivot  man  of  the 
front  rank  faces  to  the  right  in  marching  and  takes  the  half- 
step;  the  other  men  of  the  rank  oblique  to  the  right  until 
opposite  their  places  in  line,  then  execute  a  second  right  oblique 
and  take  the  half  step  on  arriving  abreast  of  the  pivot  man. 


SCHOOL  OF   THE  SQUAD 


75 


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SQUAD   TURNING   ON    FIXED    PIVOT 

1.— Squad    right    (left)  2.— MARCH  Forward    without    command 

All  glance  toward  the  marching  flank  while  at  half  step  and 
take  the  full  step  without  command  as  the  last  man  arrives  on 
the  line. 

To  TURX  ox  FIXED  PIVOT 

Being  in  line,  to  turn  and  march  :  1.  Squad  right  (left),  2. 
MARCH. 

At  the  second  command  the  right  flank  man  in  the  front  rank 
faces  to  the  right  in  marching  and  marks  time;  the  other  front 
rank  men  oblique  to  the  right,  place  themselves  abreast  of  the 
pivot,  and  mark  time.  Tn  the  rear  rank  the  third  man  from 
the  right,  followed  in  column  by  the  second  and  first,  moves 
straight  to  the  front  until  in  rear  of  his  front  rank  man,  when 
all  face  to  the  right  in  marching  and  mark  time;  the  other 
member  of  the  rear  rank  moves  straight  to  the  front  four 
paces  and  places  himself  abreast  of  the  man  on  his  right.  Men 
on  the  new  line  glance  toward  the  marching  flank  while  mark- 
ing time,  and,  as  the  last  man  arrives  on  the  line,  both  ranks 
execute  forward,  march,  without  command. 


INSTRUCTION   WITH  ARMS 

GENERAL   PROVISIONS 

The  duties  of  Signal  troops  pertain  essentially  to  the  service 
of  information.  Their  sole  arm  is  the  pistol,  which  is  furnished 
as  a  means  of  self-defense  at  such  times  when  the  scope  of 
their  duty  carries  them  beyond  the  protection  of  troops  of 
the  line. 

Thorough  training  in  the  manual  of  the  pistol  and  careful 
instruction  in  dismounted  fire  action  should  therefore  be  given 
to  insure  the  acquisition  of  that  self-reliance  and  morale  neces- 
sary for  the  performance,  unassisted  if  necessary,  of  their 
proper  functions. 

Both  before  and  after  drill  or -other  exercise  with  the  pistol, 
remove  the  magazine  to  see  that  it  is  empty  and  draw  back 
the  slide  and  examine  the  bore  to  see  that  the  pistol  is  not 
loaded. 

Before  commencing  instruction  in  the  manual,  the  soldier 
should  be  made  familiar  with  the  mechanism  of  the  pistol,  the 
names  of  the  principal  parts,  and  the  method  of  cleaning, 
assembling,  and  operating  it. 

When  a  lanyard  is  used  the  snaps  are  attached  to  the  butt 
of  the  pistol  and  the  magazine,  the  lanyard  is  passed  over 
the  head,  and  the  sliding  loop  drawn  snug  against  the  right 
armpit.  The  lanyard  should  then  be  of  just  such  length  that 
the  arm  can  be  extended  without  constraint. 

For  dismounted  instruction  with  the  pistol,  the  men  may  be 
with  or  without  intervals. 

Except  in  the  act  of  firing,  the  automatic  pistol,  when  actually 
on  the  person,  whether  loaded  or  unloaded,  will  be  carried 
cocked  and  locked.  At  all  other  times  the  hammer  will  be 
lowered  fully  down. 

Instruction  in  firing  will  conform  to  the  regulations  pre- 
scribed in  the  Small  Arms  Firing  Manual. 

76 


IXSTRCCTION  WITH  ARMS  77 

MANTAI.  OF  THE  PISTOL 

The   pistol   being  in    the   holster,   to   raise   pistol:    1.   Raise, 
2.  PISTOL. 

Raise:  Unbutton  the  flap  of  the  holster  with  the  right  hand 
and  grasp  the  stock,  back  of  the  hand  outward. 

PISTOL:  Draw  the  pistol  from  the  holster;  reverse  it,  muzzle 
up,  the  hand  holding  the  stock  with  the  thumb  and  last  three 
fingers,  forefinger  outside  the  guard,  barrel  to  the  rear  and 
inclined  to  the  front  at  an  angle  of  30",  hand  as  high  as  the 
neck  and  6  inches  in  front  of  the  point  of  the  right  shoulder. 
This  is  the  position  of  raise  pistol. 
Being  at  raise  pistol,  to  inspect  pistol :  1.  Inspection,  2  PISTOL. 

(a)  When  a  magazine  is  in  the  pistol:    Push  down  the  safety 
lock  and  lower  the  right  hand  to  within  easy  reach  of  the  left, 
pistol  pointed  upward  and   to  the   right  front  at   an   angle  of 
about   30°;   grasp   the   corrugations   of   the   slide   with   the   left 
thumb  and  forefinger,  thumb  to  the  right;  thrust  upward  with 
the  right  hand,  thus  drawing  back  the  slide  until  the  slide  stop 
is  engaged;  resume  raise  pistol. 

(b)  When  no  magazine  is  in  the  pistol:    Push  down  the  safety 
lock  and  lower  the  pistol  to  the  left  hand,  rotating  the  pistol  so 
that  the  sights  move  to  the  left,  barrel  pointing  downward  and 
to  the  left  front,  stock  pointing  upward  and  to  the  right  front ; 
with  the  left  thumb  and  forefinger  grasp  the  corrugations  of  the 
slide,  back  of  the  left  hand  down  ;  change  the  grasp  of  the  right 
hand  slightly  until  the  thumb  presses  against  the  rounded  sur- 
face of  the  slide  stop;  thrust  downward  and  to  the  left  front 
with  the  right  hand,  thus  drawing  back  the  slide,  and  at  the 
same  time  press  the  slide  stop  with  the  right  thumb  against  the 
slide  until  it  engages  ;  resume  raise  pistol. 

Inspection  pistol  is  never  executed  with  a  loaded  pistol  or 
with  a  loaded  magazine  in  the  pistol. 
1.   Return,  2.   PISTOL. 

(a)  Being  at  raise  pistol;  lock  the  pistol,  if  not  locked;  lower 
the  pistol  to  the  holster,  reversing  it,  muzzle  down,  back  of  the 
hand  to  the  right;  raise  the  flap  of.  the  holster  with  the  right 
thumb;  insert  the  pistol  in  the  holster  and  thrust  it  home;  but- 
ton the  flap  of  the  holster  with  the  right  hand. 

(b)  Being    at    inspection    pistol    (with    a    magazine    in    the 
pistol) ;  lower  the  pistol  to  the  left  hand  and  grasp  the  slide  as 
prescribed     for     inspection     pistol     without     magazine;     thrust 
downward  and  to  the  left  front  with  the  right  hand,  thus  re- 
lieving the  pressure  on  the  slide  stop,  and  at  the  same  time  dis- 
engage the  slide  stop  with  the  right  thumb;  release  the  slide; 
reverse   and  lock  the  pistol;  place  it   in  holster  as  prescribed 


78  MILITARY  SIGNAL  CORPS  MANUAL 

in  (a).  If  here  is  no  magazine  in  the  pistol,  lower  it  to  the 
bridle  hand  as  in  load;  draw  back  the  slide  and  release  it; 
lock  the  pistol  and  place  it  in  the  holster. 

When  the  last  shot  is  fired  the  slide  stop  engages  auto- 
matically. Return  pistol  is  then  executed  as  from  inspection 
pistol  (b). 

Being  at  raise  pistol,  to  insert  a  magazine  in  the  pistol: 
1.  Insert,  2.  MAGAZINE,  or  2.  LOADED  MAGAZINE. 

(a)  When   a   magazine   is   in   the   pistol:     Lower   the   pistol 
into  the  left  hand,  rotating  it  so  that  the  sights  move  to  the 
left;  grasp  the  slide  with  the  left  hand,  back  of  the  hand  down, 
barrel    pointing   downward    to    the    left    front,    stock    pointing 
upward   to  the   right   front;   release   the  magazine   catch   with 
the   middle    finger   of   the   left   hand;    withdraw    the    magazine 
with  the   right  hand;   insert  the  designated   magazine   and   re- 
sume raise  pistol.     If  there  be  no   empty  space  in   the   maga- 
zine pocket  when  the  magazine  is  withdrawn  from  the  pistol, 
the    magazine   may   be   held   between    the    left    thumb   and   the 
stock   of   the   pistol   until   the   magazine   has   been   taken   from 
the   pocket    and   inserted ;    the   magazine   withdrawn    from   the 
pistol  is  then  inserted  in  the  magazine  pocket. 

Whenever  the  magazine  catch  is  released,  the  right  hand 
should  be  so  placed  as  to  limit  the  motion  of  the  magazine  and 
prevent  its  falling  out. 

(b)  When   no   magazine   is   in   the  pistol:     Lower   the   pistol 
into  the  left  hand  and  grasp  it  as  before;  insert  the  designated 
magazine   and   resume   raise   pistol. 

A  loaded  magazine  will  never  be  inserted  without  specific 
command. 

Being  at  raise  pistol  with  a  loaded  magazine  in  the  oistol, 
to  load:  LOAD:  Push  down  the  safety  lock  and  lower  the 
pistol  to  the  bridle  hand  as  prescribed  for  inspection  pistol 
when  a  magazine  is  in  the  pistol;  operate  the  slide:  engage 
the  safety  lock  with  the  right  thumb  and  raise  pistol. 

To  simulate  loading  for  instruction,  first  withdraw  the  empty 
magazine. 

The  command  load  may  be  given  in  connection  with  the 
insertion  of  the  magazine,  for  example:  1.  Insert,  2.  LOADED 
MAGAZINE;  3.  LOAD. 

After  inserting  magazine,  reverse  the  pistol  and  load  as 
above  prescribed. 

Being  in  any  position,  to  eject  the  cartridge  from  the  re- 
ceiver: UNLOAD. 

Pass  the  pistol  into  the  left  hand  as  in  insert  magazine; 
release  the  magazine  catch  with  the  middle  finger  of  the  left 
hand,  slightly  disengaging  the  magazine;  push  down  the  safety 


INSTRUCTION  WITH  ARMS  79 

lock  with  the  right  thumb;  operate  the  slide  to  eject  the  cart- 
ridge; engage  the  magazine;  raise  and  lock  the  pistol. 

Being  in  any  position,  to  withdraw  the  magazine  from  the 
pistol:  WITHDRAW  MAGAZINE. 

Handle  the  pistol  as  in  insert  magazine;  release  the  maga- 
zine catch  ;  withdraw  the  magazine  and  execute  raise  pistol. 

Recruits  are  taught  the  motions  of  loading  and  firing  with- 
out cartridges,  and  preferably  without  a  magazine  in  the  pistol, 
to  avoid  wear  on  the  magazine  lips.  Loading  and  pointing  prac- 
tice should  be  had  at  all  gaits. 

The  hammer  is  always  lowered  preparatory  to  placing  the 
pistol  in  the  arm  rack  or  other  place  of  deposit. 

Being  at  raise  pistol,  to  lower  the  hammer  : 

(a)  Using  both  hands:   Push  down  the  safety  lock;  assume 
the  position  of  load;   seat  the  right  thumb  firmly  on  the  ham- 
mer and   hold   it   there;   raise  the   left  hand  to  the  right   and 
press    the   grip    safety   with    the   left   thumb;    insert    the   fore- 
finger inside  the  trigger  guard;  press  the  trigger  and  carefully 
let   the    hammer    down    with    the    right    thumb.     Resume   raise 
pistol. 

(b)  Using  but  one  hand:     Raise    the    right    hand    until    the 
muzzle   of   the   pistol   is   well   above   the    head;    disengage   the 
safety   lock;    seat   the   ball   of   the    right    thumb    firmly   on   the 
hammer;  bear  down  the  grip  safety  by  pressure  on  the  ham- 
mer;   press    the    trigger    and    carefully    let    down    the    hammer 
with  the  right  thumb. 

To  charge  the  magazine:  Hold  the  magazine  in  the  left 
hand,  open  end  up,  rounded  side  to  the  right.  Take  the  car- 
tridge in  the  right  hand,  thumb  on  the  rim,  bullet  end  pointing 
to  the  right ;  place  the  rim  on  the  end  of  the  magazine  fol- 
lower; force  down  the  magazine  spring  and  slip  the  cartridge 
to  the  left  of  the  magazine.  The  next  cartridge  is  similarly 
slipped  in  by  placing  it  on  the  cartridge  just  inserted  and 
forcing  down  the  spring. 

The  magazine  may  be  charged  with  any  number  of  car- 
tridges from  one  to  seven. 

Before  dismissing  the  squad,  pistols  will  be  inspected,  and 
if  found  loaded,  will  be  unloaded  and  magazines  withdrawn 
to  prevent  loaded  or  partially  loaded  magazines  being  left  in 
the  pistol.  Except  at  target  practice,  on  guard  duty,  or  active 
service,  the  pistol  is  habitually  carried  unloaded  with  empty 
magazine. 

To  FIRE 

Being  at  raise  pistol,  to  fire:  With  the  right  thumb  re- 
lease the  safety  lock,  if  in  the  locking  position  ;  extend  the  arm, 
bringing  the  sights  on  the  target,  and  press  the  trigger. 


80  MILITARY  SIGNAL  CORPS  MANUAL 

The  energy  of  recoil  causes  the  mechanism  of  the  pistol  to 
eject  the  empty  cartridge  case,  load,  and  prepare  the  pistol  for 
the  next  shot.  Pressure  must  be  entirely  relieved  from  the 
trigger  after  each  shot  in  order  that  the  trigger  may  re-engage 
the  sear.  At  the  firing  of  the  last  cartridge,  as  the  slide  moves 
to  the  rear,  it  is  automatically  locked  in  the  open  position  by 
the  slide  stop,  thus  calling  attention  to  the  fact  that  the  maga- 
zine is  empty. 

To  reload  after  firing  out  a  magazine:  Remove  the  maga- 
zine, insert  a  charged  one,  and  release  the  slide  stop  with  the 
left  hand. 

To  exercise  the  squad  in  collective  firing,  either  actual  or 
simulated  :  1.  at  (such  an  object),  2.  Ready,  3.  Squad,  4.  FIRE. 

At  the  command  ready,  the  pistols  are  cocked  or  the  safety 
latches  are  released.  At  the  command  fire,  each  man  aims  and 
fires  by  steadily  increasing  the  pressure  of  his  grip.  It  is  im- 
portant that  no  attempt  be  made-to  pull  the  trigger. 


THE  COMPANY  DISMOUNTED 

GENERAL  PROVISIONS 

The  instruction  herein  prescribed  for  the  field  company  dis- 
mounted is  applicable,  with  obvious  modifications,  to  the  platoon 
dismounted  and  the  section  dismounted.  The  organization  of  the 
various  signal  companies,  and  their  subdivisions,  will  be  found  in 
the  chapters  dealing  with  the  several  companies. 

The  lieutenants  are  assigned  as  platoon  commanders  in  numerical 
order  beginning  with  the  senior. 

POSTS  OF  OFFICERS,  NON-COMMISSIONED  OFFICERS,  ETC.,  IN  LINE 

The  captain :  Four  yards  in  front  of  the  center  of  the  company. 
Chiefs  of  platoons:  Two  yards  in  front  of  the  center  of  their 
platoons.  Master  signal  electricians:  In  the  line  of  file  closers,  op- 
posite the  center  of  the  company.  First  sergeant:  In  the  front 
rank,  1  yard  from  the  right  of  the  first  section.  Chiefs  of  sections. 
One  yard  in  front  of  the  center  of  their  sections.  Sergeants:  In 
the  front  rank  on  the  right  of  their  sections,  not  covered  in  the 
rear  rank.  Supply  stable,  and  mess  sergeants:  In  the  line  of  file 
closers.  Corporals:  In  the  front  rank  of  their  sections,  one  on 
the  left  of  the  sergeant,  the  other  on  the  left  of  the  section.  Guidon 
and  trumpeters:  In  the  line  of  file  closers,  in  rear  of  the  first 
section.  Mechanics,  cooks,  etc.,  when  present,  will  be  assigned  to 
the  various  sections. 

In  flank  columns  the  posts  are  the  same  as  when  faced  with  the 
company  from  line. 


At  the  sounding  of  the  assembly,  the  first  sergeant,  facing  the 
company,  and  6  yards  in  front  of  where  the  center  is  to  be,  com- 
mands :  1.  Fall  in,  2.  Call  rolls,  3  REPORT. 

At  the  command  fall  in,  the  sergeants  place  themselves  on  the 
line  facing  to  the  front,  in  their  proper  order,  at  sufficient  distance 
apart  for  the  formation  of  their  sections.  The  men  of  each  section 
fall  in  on  the  left  of  their  sergeants,  the  chiefs  of  sections  take 

81 


82  MILITARY  SIGNAL  CORPS  MANUAL 

their  posts,  facing  their  sections,  and  the  guidon  and  the  file  closers, 
except  the  master  signal  electricians,  take  their  posts.  The  assembly 
having  ceased,  the  first  sergeant  causes  the  sections  to  close  to  the 
right,  if  necessary. 

At  the  command  call  rolls,  the  chief  of  sections  call  the  rolls 
and  then  face  to  the  front. 

At  the  command  report,  the  chief  of  the  first  section  salutes  and 

reports,  "First  section  present,"  or  "First  section,  Corporal  

and  Private are  absent."  The  first  sergeant  having  received 

and  verified  the  report,  returns  the  salute  with  the  right  hand. 
The  chief  of  the  second  section  then  reports  in  like  manner,  and 
so  on.  Men  who  are  known  to  be  absent  by  proper  authority  are 
not  reported  absent  by  the  chiefs  of  section.  After  receiving  the 
reports  the  first  sergeant  faces  about,  salutes  the  captain  and  re- 
ports, "Sir,  the  company  is  present  or  accounted  for,"  or  "Sir  (so 
many)  non-commissioned  officers  (or  privates)  are  absent."  The 
first  sergeant  then  takes  his  post.  The  captain  places  himself  about 
12  yards  in  front  of  the  center  of  the  company,  superintends  the 
formation,  and  receives  the  report  of  the  first  sergeant,  whose  salute 
he  returns.  The  lieutenants  and  master  signal  electricians  take  their 
posts  as  soon  as  the  first  sergeant  has  reported.  During  instruction 
the  officers  have  the  saber  drawn  or  in  the  scabbard,  at  the  discre- 
tion of  the  captain.  When  the  captain  draws  saber  the  lieutenants 
also  will  draw  sabers. 

ALIGNMENTS 

The  alignments  are  executed  as  prescribed  for  the  squad,  the 
guide  being  established  instead  of  the  base  file.  In  aligning  the 
company,  the  captain  places  himself  in  prolongation  of  the  line,  2 
yards  from  and  facing  the  flank  toward  which  the  alignment  is 
made;  after  commanding  FRONT  he  resumes  his  post. 

To  DISMISS  THE  COMPANY 

Being  in  line  at  a  halt  the  captain  directs  the  first  sergeant: 
Dismiss  the  company,  and  returns  the  salute  of  the  first  sergeant. 

The  officers  and  master  signal  electricians  fall  out:  the  first 
sergeant  salutes,  steps  3  yards  to  the  front,  faces  to  the  left,  and 
commands:  DISMISSED. 

In  exceptional  cases  the  company  may  be  dismissed  from  any 
formation,  either  at  a  halt  or  marching. 

ROUTE  ORDER  AND  AT  EASE 

Marching  in  flank  column:  1.  ROUTE  ORDER,  or,  1.  AT 
EASE. 


THE  COMPANY  DISMOUNTED  83 

The  officers  carry  their  sabers  at  will  or  in  the  scabbard;  the 
men  retain  their  positions  in  ranks,  but  are  not  required  to  keep 
step. 

If  the  command  be  route  order,  the  men  are  permitted  to  talk; 
if  the  command  be  at  case,  silence  is  preserved. 

To  resume  the  cadenced  step :    1.  Company,  2.  ATTENTION. 

If  halted,  while  marching  at  route  order,  the  men  remain  at 
rest  in  ranks;  if  halted  while  marching  at  ease,  they  remain  at 
ease. 

Route  order  and  at  ease  are  not  used  while  marching  in  double 
time. 


THE    SOLDIER    MOUNTED 

STANDARD  REQUIRED 

1.  The   qualifications    of   a   good   horseman,   in    the   military 
service,  are  as  follows : 

(a)  He  should  have  a  strong  seat,  quite  independent  of  the 
reins. 

(b)  He  should  be  able  to  correctly  apply  the  aids  by  which 
a  horse  is  controlled. 

(c)  He  should  be  capable  of  covering  long  distances  on  horse- 
back with  the  least  possible  fatigue  to  himself  and  to  his  horse. 

(d)  Under  proper  directions  he  should  be  able  to  train  an 
untrained  horse  and  to  improve  a  badly  trained  one. 

(e)  He   should  have   a   practical   knowledge   of   the   care   of 
horses,  both  in  garrison  and  in  the  field;  he  should  understand 
how  to  detect  and  treat  the  minor  ailments  to  which  they  are 
liable;  and  he  should  be  a  good  groom. 

(f)  His  attention  to  the  care  and  adjustment  of  his  equip- 
ment should  be  unremitting. 

TO    STAND    TO    HEEL 

2.  The  instructor  commands :  STAND  TO  HEEL :   Each  man 
stands  at  attention  1  yard  in  rear  of  and  facing  his  heel  post. 
At  the  picket  line  he  is  1  yard  in  rear  of  and  facing  his  horse. 

TO    STAND    TO    HORSE 

3.  The    instructor    commands :    STAND    TO    HORSE:     Each 
man  places  himself,  facing  to  the  front,  on  the  left  side  of  his 
horse,  eyes  on  a  line  with  the  front  of  the  horse's  head,  so  that 
he  can  see  along  the  front,  and  takes  the  position  of  attention, 
except  that  the  right  hand,  back  uppermost,  grasps  both  reins, 

84 


THE  SOLDIER  MOV  XT  ED  85 

forefinger   between    them,   about  6   inches    from   the    bit.     The 
reins  are  on  the  horse's  neck. 

TO    LEAD    OUT 

4.  The  men  standing  to  horse,  to  leave  the  stable  or  picket 
line,  the   instructor   commands :   LEAD   OUT. 

Each  man,  holding  his  hand  well  up  and  firm,  leads  his 
horse,  without  looking  at  him,  to  the  place  designated  by  the 
instructor. 

The  men  form  in  single  rank  from  right  to  left,  and,  until 
further  orders,  with  intervals  of  3  yards. 

If  the  horse  shows  a  disposition  to  resist  being  led,  the  man 
takes  the  reins  from  the  horse's  neck,  takes  the  ends  in  the  left 
hand,  then,  with  the  right  hand  holding  the  reins,  leads  the 
horse  as  before.  When  leading  through  a  low  or  narrow  door- 
way the  horse  should  be  quieted  by  the  voice  or  caresses,  and 
not  allowed  to  pass  through  hurriedly.  To  prevent  the  horse 
from  rushing  ahead  the  instructor  may  direct  the  man  to  face 
toward  the  horse,  holding  one  rein  in  each  hand,  close  to  the 
bit,  and  lead  him  by  stepping  backward;  after  passing  the  door- 
way the  man  leads  the  horse  as  before. 

ALIGNMENTS 

5.  The   men  being  in   line   at  a  halt  at   stand  to  horse,  the 
instructor  sees   that  the  men  on  the  flank  toward  which   the 
alignment  is  to  be  made  are  in  the  desired  position  and  com- 
mands :  1.  Right  (Left),  2.  DRESS,  3.   FRONT.     Executed  as  in 
The  Soldier  Dismounted,  except  that  the  left  hand  is  not  placed 
on  the  hip,  and  each  man  moves  his  horse  forward  or  back- 
ward, as  may  be  necessary,  to  align  him.     The  instructor  may 
place  himself  on  either  flank  and  give  a  general  alignment  by 
ordering   individual   men    to   move    their   horses    backward   or 
forward. 

TO    MOUNT    (WITHOUT    SADDLE) 

6.  1.  Prepare   to   mount,  2.   MOUNT. 

At  the  first  command  drop  the  right  rein,  take  two  back  steps, 
stepping  off  with  the  left  foot,  at  the  same  time  sliding  the  right 
hand  along  the  left  rein,  face  to  the  right.  This  should  place 
the  man  behind  the  left  shoulder  of  the  horse.  Take  both 
reins  in  the  right  hand,  aided  by  the  left,  the  reins  coming  in 
on  the  side  of  the  forefinger,  forefinger  between  the  reins,  the 
loose  end  falling  over  on  the  off  side;  place  the  right  hand 
behind  the  withers,  holding  the  reins  short  enough  to  feel 


86  MILITARY  SIGNAL  CORPS  MANUAL 

lightly  the  horse's  mouth  ;  place  the  left  hand  near  the  withers, 
and  grasp  a  lock  of  the  mane,  the  lock  coming  out  between  the 
thumb  and  forefinger. 

At  the  command  mount,  spring  lightly  from  the  ground  and 
raise  the  body,  keeping  it  erect,  and  supporting  the  weight  on 
the  hands;  carry  the  right  leg,  knee  bent,  over  the  horse's 
back,  the  weight  still  borne  on  the  hands ;  sit  down  gently  on 
the  horse's  back,  and  take  one  rein  in  each  hand,  the  reins 
bearing  equally  on  the  horse's  mouth. 

POSITION    OF    THE    SOLDIER,    MOUNTED    (WITHOUT    SADDLE) 

7.  Body  balanced  on  the  middle  of  the  horse's  back.    Head 
erect  and  square  to  the  front. 

Chin  slightly  drawn  in,  but  not  so  much  as  to  produce  stiff- 
ness- 
Body  erect,  but  without  stiffness. 
Forearms    close    to    the    sides,   without    pressure.^ 
Hands  about  6  inches  apart,  backs  straight  up  and  down  and 
outward  and  held  low,  so  that  the  little  fingers  will  brush  the 
mane  on  top  of  the  withers. 

The  right  rein  in  the  right  hand  and  the  left  rein  in  the  left 
hand,  coming  in  on  the  underside  of  the  little  finger  and  com- 
ing out  over  second  joint  of  forefinger,  on  which  the  thumb 
firmly  holds  the  rein;  the  other  fingers  closed  on  the  reins, 
nails  toward  the  body;  reins  bearing  equally  on  the  horse's 
mouth  ;  bight  (end)  of  reins  falling  to  the  front  and  on  the 
right  side  of  the  horse's  neck. 

Buttocks  bearing  equally  on  the  middle  of  the  horse's  back, 
the  seat  being  as  flat  as  possible. 

Legs  stretched  by  their  weight  alone;  the  horse  clasped  by 
the  entire  leg — that  is,  the  flat  of  the  thighs,  the  inside  of  the 
knees,  and  the  calf  of  the  leg. 

Feet  hanging  naturally  and  turned  out  at  whatever  angle  the 
conformation  of  the  man  requires  in  order  to  grasp  the  horse 
as  above. 

REMARKS   ON   THE  POSITION   OF  THE   SOLDIER   MOUNTED 

8.  Body   erect    but    without    stiffness. — While    the    head    and 
shoulders    should    not    droop    forward,    nor    the    chest    be    con- 
tracted, nor  the  back  curved  to  the  rear,  and  any  tendency  to 
slouch  should  be  promptly  corrected,  still  no  part  of  the  body 
should  be  held  so  straight  or  erect  as  to  produce  stiffness. 

Forearms  close  to  the  sides  without  pressure,  to  prevent 
their  being  thrown  out  when  the  horse  trots;  if  with  pressure, 


THE  SOLDIER  MOUNTED  87 

the  motion  of  the  body  will  be  communicated  to  the  hand 
and  rein. 

Buttocks  bearing  equally,  and  seat  as  flat  as  possible,  SO  that 
the  body  will  preserve  its  steadiness. 

Flat  of  thighs,  inside  of  knees,  and  the  calf  of  the  leg  clasp- 
ing the  horse  equally  to  give  a  firm,  steady  seat. 

The  body  from  the  hips  up  should  be  movable  and  should 
yield  to 'the  motion  of  the  horse. 

The  man  should  have  hold  of  the  horse  all  the  time  with  the 
legs,  but  not  grasping  him  so  much  as  to  produce  fatigue ;  his 
legs  from  the  inside  of  the  thighs  and  knees  and  calf  should 
be  in  constant  contact  with  the  horse,  but  not  so  much  so  as  to 
produce  fatigue  in  the  man.  The  arms  should  be  without  stiff- 
ness at  the  shoulders  to  avoid  communicating  the  motion  of 
the  body  to  the  reins. 

The  hands  take  a  gentle  feel  of  the  horse's  mouth,  but  other- 
wise are  stationary,  except  to  direct  the  horse. 

During  the  early  lessons  the  position  of  the  soldier  is  neces- 
sarily one  of  constraint.  He  will  probably  be  much  fatigued 
and  possibly  made  sore  in  tendons  and  muscles.  An  effort 
should  be  made  to  teach  him  to  ride  without  unnecessary  fa- 
tigue or  injuring  him  physically  and  without  putting  him  to 
anything  which  will  tend  to  destroy  his  confidence  on  a  horse 
or  his  "nerve." 

No  man  can  be  said  to  be  a  good  horseman  who  has  not 
a  firm,  well-balanced  seat  and  good  hands  ;  these  are  therefore 
of  the  utmost  importance;  they  will  assist  the  horse;  the  want 
of  them  will  impede  the  horse's  actions  and  make  sore  backs. 

THE    RESTS 

9.  Being  at  stand  to  horse,  the  commands  are:  AT  EASE 
and  REST,  which  are  executed  as  prescribed  in  The  Soldier 
Dismounted,  except  that  each  soldier  retains  his  hold  of  the 
reins  to  keep  his  horse  in  place. 

Being  mounted  and  at  a  halt,  the  commands  are :  AT  EASE 
and  REST;  if  marching.  ROUTE  ORDER.  At  the  command  at 
ease  the  soldier  may  turn  his  head  and  make  slight  changes 
of  position,  but  preserves  silence. 

At  the  command  rest  or  route  order,  the  soldier  may  turn 
his  head,  may  talk,  and  make  slight  changes  of  position,  but 
must  not  lounge  on  his  horse. 

To  resume  the  attention:  1.  Squad,  2.  ATTENTION.  The 
soldier,  if  dismounted,  takes  the  position  of  stand  to  horse;  if 
mounted,  he  takes  the  position  of  the  soldier  mounted. 


88  MILITARY  SIGNAL  CORPS  MANUAL 

If  the  squad  be  mounted,  attention  may  be  resumed  by  the 
command:  1.  REINS. 

TO    DISMOUNT     (WITHOUT    SADDLE) 

10.  1.  Prepare  to  dismount,  2.  DISMOUNT. 

At  the  first  command  pass  the  right  rein  into  the  left  hand, 
then  seize  both  reins  with  the  right  hand,  in  front  of  the  left, 
forefinger  between  the  reins,  and  place  the  right  hand  on  the 
withers,  the  reins  coming  into  the  hand  on  the  side  of  the  fore- 
finger; let  go  with  the  left  hand  and  grasp  a  lock  of  the  mane 
in  front  of  the  withers,  the  lock  coming  out  between  the  thumb 
and  forefinger. 

At  the  command  DISMOUNT,  raise  the  body  on  both  hands, 
carry  the  right  leg,  knee  bent,  over  the  horse's  back  without 
touching  it ;  bring  the  right  leg  near  the  left  and  come  lightly 
to  the  ground  on  the  balls  of  the  feet,  bending  the  knees  a 
little ;  face  to  the  left,  drop  the  right  rein,  step  to  the  front, 
sliding  the  right  hand  along  the  left  rein,  and  take  the  posi- 
tion of  stand  to  horse. 

TO  LENGTHEN  OR   SHORTEN  THE  REINS 

11.  Bring   the    hands    toward    each    other;    grasp    the    right 
rein  with  the  thumb   and   forefinger  of  the   left   hand  a   short 
distance   from  the  right   thumb;   relax  the  grasp  of  the   right 
hand   and   allow   the   rein    to   slip    through    to   get    the    proper 
bearing;  then  close  the  right  hand  and  replace  the  hands.   With 
the  left  rein  the  positions  of  the  hands  are  reversed. 

TO   TAKE   THE  REINS   IN    ONE   HAND 

12.  To  relieve  the  constraint  of  the  arms  by  changing  their 
position,  as  well  as  to  prepare  the  men  for  the  use  of  the  curb 
bridle,    the    instructor    commands :    1.    In   left    (right)    hand,   2. 
TAKE  REINS. 

At  the  second  command  bring  the  left  hand  opposite  the 
middle  of  the  body;  half  open  and  place  in  it  the  right  rein, 
holding  both  reins  as  explained  for  the  left  rein,  except  that 
the  little  finger  separates  the  reins,  the  right  rein  coming  in 
about  the  little  finger;  close  the  left  hand  and  drop  the  right 
hand  behind  the  thigh. 

TO    ADJUST    THE    REINS 

13.  Seize   the   bight   with    the    thumb   and   forefinger   of   the 


THE  SOLDIER  MOUNTED  89 

right  hand;  partly  open  the  left  hand  so  as  to  allow  the  reins 
to  slip  through  it;  raise  the  right  hand  until  the  reins  bear 
equally;  close  the  left  hand  upon  them,  letting  the  bight  fall 
over  the  forefinger  and  right  rein;  drop  the  right  hand. 

TO    RETAKE    THE    REINS    IN    BOTH     HANDS 

14.  The   reins   being  in   the  left   hand:   1.   In  both  hands,  2. 
TAKE   REINS. 

Half  open  the  left  hand,  seize  with  the  right  hand  the  right 
rein,  and  hold  them  as  previously  described. 

TO   DROP   AND   RETAKE   REINS 

15.  Drop  reins:  Drop  the  reins  on  the  horse's  neck  near  the 
withers  and  drop  the  hands  behind  the  thighs. 

Take  reins:  The  man  retakes  the  reins  and  holds  them  as 
before  dropping  them. 

TO    MOUNT    FROM    THE    RIGHT    SIDE 

16.  Executed    as    in    mounting    from    the    left    side,    but    by 
inverse  means. 

17.  If  the  command  be  mount  the  men  execute  all  that  has 
been  prescribed  for  prepare  to  mount  and  mount. 

TO    DISMOUNT    OX     THE    RKiHT     SIDE 

18.  1.  To  the  right,  2.  Prepare  to  dismount,  3.  DISMOUNT. 

Executed  as  in  dismounting  from  the  left  side,  by  inverse 
means. 

19.  The  men  are  frequently  practiced  in  mounting  and  dis- 
mounting on  the  right  side. 

20.  If  the  command  be  DISMOUNT,  the  men  execute  all  that 
has  been  prescribed  for  prepare  to  dismount  and  DISMOUNT. 

TO    DISMISS     THE     SQUAD 

21  The  squad  being  in  line  at  stand  to  horse:  1.  By  the 
right  (left,  or  right  and  left),  2.  FALL  OUT. 

The  man  on  the  right  leads  his  horse  1  yard  to  the  front 
and  then  directly  to  the  stable  or  picket  line.  Each  of  the 
other  men  executes  in  succession  the  same  movement  so  as  to 
follow  the  horse  next  on  the  right  at  a  distance  of  1  yard. 

Being  in  column  of  files  or  twos,  at  the  command  FALL 
OUT,  the  leading  rider  or  the  rider  on  the  right  of  each  two 
leads  out  as  prescribed  and  is  followed  by  the  other  riders  in 
turn. 


90  MILITARY  SIGNAL  CORPS  MANUAL 

The  men  remove,  clean,  and  put  the  equipments  in  place, 
and  care  for  and  secure  their  horses  under  the  direction  of 
the  instructor. 

The  instructor,  having  satisfied  himself  by  inspection  that 
the  horses  and  equipments  are  properly  cared  for,  and  that 
the  precautions  required  for  the  care  of  horses  on  their  return 
from  exercise  have  been  observed,  orders  that  the  men  be 
fallen  in,  marched  to  the  company  parade,  and  dismissed. 

GAITS    OF    HORSES 

22.  The  gaits  are  the  walk,  trot,  canter,  and  gallop. 

The  walk  is  at  the  rate  of  4  miles  an  hour,  or  1  mile  in  IS 
minutes,  or  1\71A  yards  in  a  minute. 

The  maneuvering  trot  is  at  the  rate  of  8  miles  an  hour,  or  1 
mile  in  7l/2  minutes,  or  234^  yards  a  minute.  For  purposes  of 
individual  instruction,  the  rate  of  «the  trot  may  be  diminished 
to  the  rate  of  6  or  6l/2  miles  an  hour  by  the  command  SLOW 
TROT.  At  the  command  trot  out,  the  rate  is  8  miles  an  hour. 

The  canter  is  at  the  rate  of  8  miles  an  hour  and  is  generally 
used  for  individual  instruction. 

The  maneuvering  gallop  is  at  the  rate  of  12  miles  an  hour, 
or  1  mile  in  5  minutes,  or  352  yards  a  minute. 

The  length  of  the  stride  is  about  10  feet. 

The  full  or  extended  gallop  is  at  the  rate  of  16  miles  an  hour. 

To  instruct  in  the  maneuvering  cadences,  stakes  are  placed 
on  the  drill  ground,  on  a  convenient  line  for  a  long  track.  \\7l/3 
yards  apart.  The  men  and  guides  are  required  to  march  over 
the  spaces  at  the  rate  of  one,  two,  three,  or  four  per  minute, 
according  as  the  gait  is  the  walk,  trot,  canter,  gallop,  or  full 
gallop. 

Instruction  in  each  gait  should  be  practiced  individually  and 
collectively  until  each  man  knows  whether  he  has  the  proper 
speed  or  cadence  by  the  rhythm  of  motion. 

Horses  may  be  trained  to  walk  in  column  under  favorable 
conditions  4l/2  miles  an  hour,  making  125  steps  a  minute,  the 
stride  being  0.916  yard. 

The  average  walk  of  a  horse  is  a  mile  in  16  minutes,  3.75 
miles  an  hour,  making  120  steps  (110  yards)  per  minute,  the 
strides  being  0.916  yard. 

The  average  trot  of  a  horse  is  a  mile  in  8  minutes,  7.5  miles 
an  hour,  making  180  steps  (220  yards)  per  minute,  the  stride 
being  1.22  yards. 


THE  SOLDIER  MOUNTED  91 

ANALYSIS    OF    GAITS 
The  Walk 

23.  The  walk  is  a  gait  in  which  the  feet  are  lifted  in  suc- 
cession   and   put    down    in    the    order    of   their   lifting.      If   the 
right  front  foot  begins  the  gait,  the  other  feet  are  lifted  in  the 
following  order :    Left  hind,  left   front,   right  hind.     The  walk 
should  be  free,  easy,  and  elastic. 

The  Trot 

24.  The  trot  is  a  gait  at  which  the  horse  springs  from  one 
diagonally    disposed    pair    of    feet    to    the    other;    between    the 
beats  all  the  feet  are  in  the  air.     The  right  front  and  the  left 
hind  are  called  the  right  diagonal,  the  left  front  and  the  right 
hind  the  left  diagonal. 

The  Gallop 

25.  The  gallop  is  the  most  rapid  of  gaits.     It  must  not  be 
used   unnecessarily   over   long   distances,   particularly   on    hard 
roads,  where  the  concussion  on  the  feet  is  severe,  nor  when  the 
saddle  is  packed.     However,  when  the  rapidity  of  the  normal 
trot  is  not  sufficient,  the  rider,  when  out  alone,  should  take  the 
gallop  in  preference  to  increasing  the  speed  of  the  trot. 

The  horse  is  said  to  lead  right  when  the  feet  on  the  right 
side  are  more  advanced  than  the  corresponding  feet  on  the 
left  side.  When  the  feet  are  advanced  in  the  inverse  order 
the  horse  is  said  to  lead  left. 

The  gallop  is  marked  by  three  beats  and  a  period  of  suspen- 
sion. If  the  horse  be  leading  right,  the  first  beat  is  marked  by 
the  left  hind  foot,  the  second  by  the  nearly  simultaneous  plac- 
ing of  the  right  hind  and  left  front  feet,  and  the  third  by  the 
placing  of  the  right  front  foot.  The  horse  then  leaps  into  the 
air  from,  and  advances,  the  right  front  foot.  In  leading  left 
the  beats  are  right  hind,  left  hind,  and  right  front,  left  front. 

A  horse  gallops  true  when  he  leads  right  in  turning  to  the 
right,  and  leads  left  in  turning  to  the  left. 

He  gallops  false  when  he  leads  left  in  turning  to  the  right, 
or  conversely.  A  horse  is  united  when  he  gallops  right  (left) 
in  front  and  right  (left)  behind.  He  is  disunited  when  he 
gallops  right  in  front  and  left  behind,  or  conversely. 

The  gallop  should  be  begun  on  the  circle,  because  the  feet 
are  then  favorably  placed  for  taking  and  maintaining  the  proper 
lead.  The  horses  thus  start  off  more  calmly  and  the  rider  is 


92 

enabled  to  regulate  the  pace  by  describing  a  circle  of  greater 
or  less  circumference. 

As  soon  as  the  horse  breaks  into  the  gallop  the  rider  should 
move  in  cadence  with  his  horse.  The  back  and  legs  unite  in 
the  rhythm  of  the  gait,  the  hands  accompany  gently  and  with* 
out  exaggeration  the  movements  of  the  head  and  neck. 

During  the  gallop  the  command  at  ease  is  frequently  given. 
The  riders  execute  the  suppling  exercises  which  have  been  in- 
dicated as  necessary  in  each  case;  they  abandon  themselves 
completely  to  the.  motion  of  the  horse  and  thus  acquire  ease 
and  flexibility.  Prolonged  periods  at  the  gallop  on  calm  and 
free-moving  horses  are  most  favorable  for  easily  obtaining  this 
result. 

The  canter  is  the  collected  or  school  gallop. 

TO  MOUNT  (WITH  SADDLE) 

26.  1.  Prepare  to  mount,  2,  MOUNT. 

At  the  first  command  drop  the  right  rein,  taking  two  back 
steps,  stepping  off  with  the  left  foot,  at  the  same  time  sliding 
the  right  hand  along  the  left  rein;  half  face  to  the  right;  this 
should  place  the  man  about  opposite  the  girth ;  with  the  aid  of 
the  left  hand  take  both  reins  in  the  right,  forefinger  between 
the  reins,  and  place  the  right  hand  on  the  pommel,  the  reins 
coming  into  the  hand  on  the  side  of  the  forefinger,  and  held  so 
as  to  feel  lightly  the  horse's  mouth,  the  bight  falling  on  the 
right  side.  Place  a  third  of  the  left  foot  in  the  stirrup,  with 
the  assistance  of  the  left  hand,  if  necessary;  rest  upon  the  ball 
of  the  right  foot;  grasp  a  lock  of  the  mane  with  the  left  hand, 
the  lock  coming  out  between  the  thumb  and  forefinger. 

At  the  command  mount,  spring  from  the  right  foot,  holding 
firmly  to  the  mane  and  keeping  the  right  hand  on  the  pommel; 
pass  the  right  leg,  knee  bent,  over  the  croup  of  the  horse  with- 
out touching  him;  sit  down  gently  in  the  saddle;  let  go  the 
mane,  insert  the  right  foot  in  the  stirrup,  pass  the  reins  into 
the  left  hand  and  adjust  them. 

POSITION   OF   THE   SOLDIER,    MOUNTED    (WITH    SADDLE) 

27.  Same    as    previously    explained    (par.    7),    with    the    fol- 
lowing exceptions  :  Buttocks  bearing  equally  and  as  flat  as  pos- 
sible upon  the  middle  of  the  saddle;  reins  coming  into  the  left 
hand  on   the   side  of  the   little   finger,  and  leaving  it  between 
thumb  and  forefinger;  little  finger  between  the  reins,  right  rein 
above  it;  the  other  fingers  closed,  thumb  pointing  to  the  right 
front  in  the  prolongation  of  the  forearm  and  pressing  the  reins 
firmly  on  second  joint  of  forefinger,  the  end  of  the  reins  falling 


THE  SOLDIER  MOUNTED  03 

to  the  front  and  outside  of  the  right  rein  ;  left  forearm  close  to 
the  body  without  pressure;  the  back  of  the  hand  nearly  ver- 
tical; left  hand  in  front  of  the  pommel  of  the  saddle  and  as 
close  to  the  top  of  the  horse's  withers  as  possible,  without  rest- 
ing upon  the  pommel;  right  hand  behind  the  thigh,  arm  hang- 
ing naturally;  feet  inserted  in  the  stirrups  so  that  the  ball  ot 
the  foot  rests  on  the  tread  of  the  stirrup,  heel  slightly  lower 
than  the  tread. 

STIRRUPS 

28.  The  stirrups  should  support  the  feet  and  the  weight  of 
the  legs  only  and  be  of  such  length  that  when  the  legs  are  in 
proper  position,  the  feet  out  of  the  stirrups,  the  treads  will  be 
on  a  level  with  the  lower  part  of  the  inner  ankle  bone. 

The  length  depends  somewhat  on  the  formation  of  the  man ; 
a  man  with  a  thick,  heavy  thigh  requires  a  shorter  stirrup  than 
a  man  with  a  thin,  flat  one.  For  long  distances  at  the  gallop 
and  trot  a  shorter  stirrup  is  required  than  at  a  walk. 

When  riding,  the  stirrups  take  up,  in  a  measure,  the  weight 
of  the  body  in  its  descent  to  the  saddle,  by  yielding  of  the 
ankles  to  prevent  shock.  This  action  is  an  easy,  quick  stiffen- 
ing of  the  muscles,  which  distributes  the  downward  motion 
between  the  feet,  thighs  and  seat. 

If,  after  the  man  has  exercised  a  short  time  at  the  slow 
trot,  he  has  a  close  seat,  his  leg  in  proper  position,  with  his 
heel  down,  but  does  not  easily  keep  his  stirrup,  then  the  stirrup 
requires  shortening. 

THE    DOUBLE    BRIDLE 

29.  The  general  principles  for  the  use  of  the  reins,  already 
explained   for  the  snaffle  bridle,  apply  to   the  management  of  the 
horse  with   the   double  bridle,   except   that   the   bridle   hand   is 
moved  instead  of  both  hands.     In   all  movements  of  the  hand 
the  arm  should  act  freely  and  without  constraint  to  the  body, 
and  as  the  curb  bit  is  much  more  severe  than  the  snaffle  bit, 
it  must  be  applied  gradually  and  more  gently,  particularly  in 
halting  and  in  reining  back. 

To  turn  the  horse  to  the  right  (left):  Carry  the  hand  a  little 
forward  and  to  the  right  (left),  so  that  the  left  (right)  rein 
bears  on  his  neck. 

INSTRUCTION    WITH    SADDLE,   DOUBLE   BRIDLE,   AND   SPURS 

30.  The  instructor  causes  recruits  at  first  to  use  the  saddle 
and   snaffle   bit   in    executing   movements    prescribed   and    does   not 


94  MILITARY  SIGNAL  CORPS  MANUAL 

give  them  the  curb  bit  and  spurs  until  they  have  confidence  in 
their  seat  and  are  able  to  ride  fairly  well. 

As  a  general  rule,  soon  after  commencing  the  use  of  the 
saddle  in  the  riding-hall  exercises,  about  one-half  the  time  of 
each  drill  may  be  without  saddles,  the  saddles  being  removed 
and  conveniently  placed  in  the  hall. 

A  man  who  can  ride  bareback  can  ride  with  a  saddle. 

RIDING    WITHOUT    REINS    AND    STIRRUPS 

31.  Riding   without    reins    should    be    begun    with    the    very 
first  mounted  lesson,  and  thereafter  throughout  the  elementary 
instruction   a   portion  of  each   lesson   should  be   devoted   to  it. 

The  instructor  causes  the  riders  to  take  the  track  behind  a 
leader,  and  to  drop  their  reins  as  soon  as  their  horses  are 
going  quietly  and  smoothly.  For  the  first  few  lessons  the  gait 
is  confined  to  the  walk,  then  as  confidence  is  established  it  is 
pushed  to  the  trot  and  later  to  the  gallop.  At  each  gait  stir- 
rups should  be  retained  until  the  riders  have  lost  all  sign  of 
nervousness,  when  they  should  be  abandoned  and  the  work 
continued  without  reins  or  stirrups. 

When  riding  without  reins  the  instructor  causes  the  men  to 
fold  their  arms  in  front  of  their  bodies,  or  place  their  hands  on 
the  hips,  overhead,  to  the  side,  to  the  front,  or  to  hold  them 
as  though  they  were  holding  the  reins,  and  at  the  same  time 
he  sees  that  they  do  not  derange  their  seats.  The  movement 
of  the  arms  in  this  manner  assists  in  bringing  about  relaxa- 
tion and  in  acquiring  balance. 

When  riding  without  reins  for  the  first  few  times,  it  may  be 
found  advantageous  with  some  men  to  have  their  horses  led 
by  an  instructed  soldier,  who,  in  this  case,  may  be  either 
mounted  or  dismounted.  Another  method  is  to  put  the  horse 
on  the  longe  for  the  first  few  lessons  without  reins. 

TO    DISMOUNT    (WITH    SADDLE) 

32.  1.  Prepare  to  dismount,  2.  DISMOUNT. 

At  the  first  command  seize  the  reins  with  the  right  hand,  in 
front  of  and  near  the  left,  forefinger  between  the  reins,  so  that 
they  come  in  on  the  side  of  the  forefinger;  place  the  right 
hand  on  the  pommel;  let  go  with  the  left  hand,  grasp  a  lock  of 
the  mane,  the  lock  coming  out  between  the  thumb  and  fore- 
finger; take  the  right  foot  out  of  the  stirrup;  partly  disengage 
the  left  foot,  body  erect. 

At  the  command  DISMOUNT,  rise  upon  the  left  stirrup,  pass 
the  right  leg,  knee  bent,  over  the  croup  of  the  horse  without 


THE  SOLDIER  MOUNTED  95 

touching  him;  descend  lightly  to  the  ground,  remove  the  left 
foot  from  the  stirrup  and  place  it  by  the  side  of  the  right, 
body  erect;  let  go  the  mane;  place  the  end  of  the  reins  on  the 
neck  near  the  pommel  of  the  saddle  with  the  right  hand,  which 
then  seizes  the  left  rein;  face  to  the  left,  take  two  short  steps, 
left  foot  first,  slipping  the  right  hand  along  the  left  rein,  and 
take  the  position  of  stand  to  horse. 

GATHERING  THE    HORSE 

33.  Before  the  horse  is  required  to  execute  aay  movement 
he  should  be  given  a  preparatory  signal.     This   signal   should 
be  given   at   the   time  of  the  preparatory  command  or   signal. 
Whatever  the  movement  to  be  executed,  the  signal  is  always 
the  same.    Its  object  is  to  attract  his  attention  and  to  prepare 
him  for  a  movement.     This  is  called  gathering  the  horse. 

Having  a  light  pressure  of  the  bit  against  the  horse's  mouth 
and  a  light  feel  of  the  lower  legs  against  his  sides,  the  rider,  in 
order  to  gather  him,  increases  the  pressure  of  the  lower  legs, 
with  heels  well  shoved  down,  and  slightly  increases  the  tension 
of  the  reins.  These  pressures  are  increased  intermittently  until 
the  elastic  movement  of  the  horse  under  the  rider  indicates  that 
the  former  has  observed  the  signal. 

If,  when  at  a  halt,  the  horse  backs,  or  when  marching  de- 
creases the  gait,  the  tension  applied  to  the  reins  has  been  too 
great.  If,  when  at  a  halt,  the  horse  moves  forward,  or  when 
marching  he  increases  the  pace  or  gait,  the  impulse  given  with 
the  legs  has  not  been  met  or  controlled  by  the  reins. 

Each  force  should  exactly  balance  the  other,  and  the  horse, 
held  between  the  two,  should  feel  responsive  to  the  indications 
and  aids  of  the  rider. 

TO   MOVE   FORWARD 

34.  Being  at   a  halt:   1.  Forward,  2.  MARCH.     At   the   first 
command  the  rider  gathers  the  horse;  at  the  second  he  simul- 
taneously  (1)   pushes  his  buttocks  to  the  front,   (2)   acts  with 
both  legs  according  to  the  temperament  of  the  horse,  (3)  eases 
the  reins  by  slightly  relaxing  the  fingers  and  giving  the  wrist, 
without  losing  contact.    The  aids  cease  to  be  active  as  soon  as 
obedience  is  obtained. 

TO    HALT 

35.  Being  at  the  walk  :  HALT.    The  rider  sits  well  down  in 
the  saddle  and  gathers  the  liorse;  he  then  simultaneously  (1) 


96  MILITARY  SIGX.1L  CORPS  MANUAL 

closes  the  fingers  on  the  reins,  bending  the  wrist,  and  if  neces* 
sary,  moving  the  hands  in  and  back  with  the  body;  (2)  slightly 
increases  the  pressure  of  the  legs;  (3)  imposes  the  weight  of  his 
body  against  the  horse's  back  by  convexing  his  loins  backward. 

As  soon  as  the  horse  slackens  the  gait  ever-so  little  the  pres- 
sure of  the  fingers  and  legs  is  slightly  relaxed  to  reward  him 
for  his  obedience.  It  is  then  reapplied  and  again  relaxed  until 
the  horse  has  completed  the  movement  desired. 

In  order  to  prevent  the  horse  from  halting  entirely  on  the 
forelegs,  the  rider  must  increase  the  pressure  of  his  legs  to 
induce  the  horse  to  engage  his  hind  legs  farther  under  the  mass. 
By  convexing  his  loins  and  imposing  his  weight  against  the  mus- 
cular activity  of  the  horse's  back,  the  rider  limits  the  function- 
izing  of  the  muscles  which  control  impulsion  and  thus  permits 
the  hind  legs  to  participate  in  stopping  or  in  reducing  the  gait. 
It  is  faulty  to  lean  back  in  an  exaggerated  position,  because  of 
the  tendency  to  permit  the  legs  and  thighs  to  go  forward  and 
to  act  with  a  dead  pull  of  the  reins  on  the  horse's  mouth;  if 
done  abruptly,  it  is  painful  to  a  horse  and  may  cause  him  to 
halt  in  a  hard  and  jolty  manner. 

In  reducing  the  gait  a  steady  pull  against  the  mouth  must 
be  particularly  avoided. 

THE    HALF    HALT 

36.  The  half  halt  finds  constant  application  in  the  training 
of  both  horse  and  rider.     It  is  a  brief,  energetic  action  of  the 
hands,  which  the  rider  executes  with  the  fingers  closed  on  the 
reins   by   twisting  the   wrist   quickly   from  below   upward   and 
from  front  to  rear,  without  losing  contact  and  without  stopping 
the  horse.    At  the  same  time  the  rider  momentarily  closes  his 
legs    and    convexes    his    loins    as    in    the    halt.      The    half    halt    is 
used  to  slow  up  horses  that  are  too  ambitious  or  to  carry  to 
the  rear  the  excess  of  weight  that  some  badly  balanced  horses 
allow  to  come  on  the  shoulders.  It  is  effected  according  to  need, 
on  one  rein,  on  two  together,  on  the   snaffle,  or  on  the  curb. 
The  hand   should  regulate  the  power  of  its  action  by  the  re- 
sistance  of  weight  which   it  meets. 

CHANGES    OF   GAIT 

37.  To  pass  from  the  halt  or  the  walk  to  the  trot,  canter, 
or  gallop,  the  means  prescribed  for  passing  from  the  halt  to  the 
walk    are    employed    and    continued    until    the    desired    gait    is 
taken. 

To  pass  from  a  faster  to  a  slower  gait,  or  to  a  halt,  the 
means  prescribed  for  passing  from  the  walk  to  the  halt  are 


THE  SOLDIER  MOUNTED  97 

employed    and   continued    until   the    desired   gait    is   taken    or 
the  horse  has   stopped. 

The  commands  are:  1.  Trot,  2.  MARCH;  1.  Gallop,  2. 
MARCH;  .1  Canter,  2.  MARCH;  1.  Walk,  MARCH;  and  HALT. 

EXTENDING     OR     REDUCING     SPEED     AT     VARIOUS     GAITS 

38.  To   extend  or   reduce   the   speed   at   any  gait   the   rider 
employs  the  means  prescribed  for  passing  from  the  halt  to  the 
walk  or  from  the  walk  to  the  halt  to  the  extent  necessary  to 
obtain  the  desired  results. 

The  horse  in  extending  the  walk  increases  the  amplitude  of 
the  movement  of  his  head  and  neck  to  the  same  degree  as  he 
increases  the  length  of  his  step;  he  accelerates  the  movement 
of  the  head  as  he  increases  the  cadence  or  tempo  of  his  step. 

The  rider  aids  these  movements  by  yielding  the  hand  and 
giving  the  horse  greater  freedom  of  movement.  He  maintains 
contact  so  that  he  can  exercise  gradual  restraining  influence 
with  the  direct  rein  when  he  feels  the  horse  is  about  to  spring 
into  the  trot. 

To  reduce  the  walk  the  rider  makes  use  of  the  direct  rein 
and  legs  as  in  coming  to  the  halt.  The  step  is  shortened  and 
the  cadence  or  tempo  decreased. 

To  extend  or  reduce  the  trot,  the  same  means  are  used.  The 
exercises  in  extending  and  reducing  the  gait  afford  excellent 
practice  for  the  rider  in  the  use  of  the  aids  and  good  training 
for  the  horse  in  obeying  them,  but  the  soldier  out  of  ranks 
should  use  only  the  regulation  gaits. 

Changes  of  speed  are  executed  at  the  commands:  1.  Slow 
walk  (trot  or  gallop),  2.  MARCH;  or,  1.  Walk  (trot)  out,  2. 
MARCH;  or  Extended  gallop,  2.  MARCH.  The  normal  speed 
is  taken  at :  1.  Walk  (trot  or  gallop),  2.  MARCH. 

To  increase  or  decrease  the  cadence  or  tempo  at  any  gait 
the  instructor  may  caution  :  Extend  (Reduce)  the  gait. 

INDIVIDUAL  MOUNTED  DRILL  AND  INSTRUCTION 

39.  Wherever  formation  in  line  is  prescribed  in  these  regu- 
?ations,  it  will  be  understood,  unless  indicated  to  the  contrary, 
that  line  without  intervals  is  intended. 

TO    FORM    IN    LINE    WITH    INTERVALS 

40.  To  form  in  line  with  intervals  the  instructor  designates 
a  trooper  to  act  as  the  base  of  the  formation,  indicates  to  such 
trooper  the  point  where  the  right  of  the  squad  is  to  rest  and 
the   direction   in  which  the   line  is   to  face,  takes  position   at  a 


98  MILITARY  S1GXAL  CORPS  MAXUAL 

convenient  distance  in  front  of  and  facing  the  point  where  the 
center  is  to  rest,  and  commands:  LEAD  INTO  LINE  WITH 
INTERVALS.  The  base  trooper  leads  out  and  takes  position 
as  indicated;  the  other  troopers  lead  out  so  as  to  approach 
the  line  successively  directly  from  the  rear  and  in  single  rank 
form  on  the  line  established  by  the  base  trooper,  in  order 
from  right  to  left.  The  troopers  form  at  stand  to  horse  with 
intervals  of  3  yards  between  horses. 

BEING  IN  LINE  WITH   INTERVALS,  TO  MARCH  BY  THE  FLANK  IN  COLUMN 

OF    FILES 

41.  1.  By  the  right  (left)  flank,  2.  MARCH. 

At  the   first   command  gather  the   horse. 

At  the  command  march,  open  the  right  rein  and  close  both 
legs,  the  right  leg  a  little  more  to  the  rear  than  the  other; 
turn  to  the  right  by  moving  the  horse  over  a  quarter  of  a 
circle  whose  radius  is  2  yards;  when  the  turn  is  nearly  ended 
diminish  the  effect  of  the  right  rein  and  leg,  using  the  left  rein 


(f  If  fi"  0" 


and  leg  to  straighten  the  horse ;  when  the  turn  is  completed, 
relax  both  legs  and  move  off  at  a  right  angle  to  the  original 
direction.  The  effect  of  the  rein  is  to  lead  the  horse  in  the 
desired  direction,  not  to  pull  him  back  on  that  side. 

Whenever  executing  the  individual  turn  at  the  trot  or  gallop, 
the  effect  if  the  outer  (in  this  case  the  left)  leg  should  be 
increased  to  sustain  the  horse. 

42.  A  squad  marched  by  the  flank,  from  line  with  intervals, 
is  in  column  of  files,  with  the  distance  of  4  feet  from  the  head 
of  one  horse  to  the  croup  of  the  horse  next  in  front. 

Marching  in  column  of  files,  each  soldier  should  so  conduct 
his  horse  that  the  soldier  next  in  front  of  him  shall  hide  all 
others  in  front;  all  follow  in  the  trace  of  the  conductor  or 
leading  file. 

Distances,   when    lost,    should   be    regained   gradually. 

If  the  column  of  files  be  marched  by  the  flank,  the  squad  will 
then  be  in  line  with  intervals  of  3  yards  between  files. 

43.  For  convenience  in   estimating  spaces,  each   horse   with 
his   rider    is    considered   as    occupying   a    space    of   3   yards    in 
length  and  1  yard  in  width,  but  by  measurement  the  horse  oc~ 
cupies  only  about  8  feet  in  length. 


THE  SOLDIER   MOl'XTED  99 

44.  To  halt  the  column  of  files  :  1.  Squad,  2.  HALT,  and  to 
resume   the   march :   1.   Forward,  2.   MARCH. 

TO  C'HAXGE   DIRECTION' 

45.  At  a  walk  the  changes  of  direction  are  made  on  the  arc 
of  a  circle  the  radius  of  which  is  2  yards.    At  fast  gaits,  where 
the   horse   is   more   or  less   extended  and  therefore   harder   to 
bend,  the  radius  of  the  turn  must  be  correspondingly  increased. 

46.  Being   in    column   of   files:    1   Column   right   (left);    or,   1. 
Column  half  right  (half  left),  2.  MARCH. 

The  leading  man  turns  or  half  turns  to  the  right  at  the  com- 
mand of  execution  and  marches  in  the  new  direction  ;  the  other 
men  move  forward  and  turn  successively  on  the  same  ground. 

THE    INDIVIDUAL    ABOUT 

47.  Being   in    line   with    intervals,   or   in    column    of   files :    1. 
Right  (left)  about,  2.  MARCH. 


f'YYY 


Each  man  turns  his  horse  on  a  half  circle  whose  radius  is 
2  yards,  a'nd  then  moves  off  in  the  new  direction,  to  the  former 
rear. 

TO    OBLIQUE 

48.  Being  in  line  or  in  column  of  files :  1.  Right  (left) 
oblique,  2.  MARCH. 

Each  man  turns  his  horse  half  right  on  an  eighth  of  a 
circle,  and  then  moves  at  an. angle  of  45°  to  his  former  di- 
rection. 


100  MILITARY  SIGXAL  CORl'S  &ANUAL 

To  resume   the   original   direction  :   1.   Forward,  2.  MARCH. 
Each  man   turns   half   left  and  then   moves   forward. 

TO    TURN    OX    THE    FOREHAND 

49.  Being  in  line  or  column  at  the  halt:  1.  On  the  forehand, 
2.     To    the    right    (left),    or,    2.     To    the    right    (left)    about,    3. 

MARCH.  The  horse  is  first  put  up  against  the  hit,  or  gathered. 
The  rider  then  takes  a  slight  set  of  the  head  toward  the  side 
of  the  turn.  The  inner  right  leg  is  applied  behind  the  girth  and 
when  necessary  is  accompanied  by  the  action  of  the  inner  rein. 
The  haunches  are  swung  step  by  step  around  the  opposing  fore- 
hand until  a  turn  of  90°  or  180°,  respectively,  is  completed. 
Every  step  of  the  haunches  is  regulated  accurately  by  the  outer 
supporting  leg  applied  behind  the  girth  in  such  a  manner  that 
there  is  a  decided  pause  between  steps,  thereby  preventing  the 
haunches  from  rushing.  Both  during  and  after  the  movement 
the  rider's  legs  and  seat  should  insure  that  the  horse  does  not 
back  but  remains  up  against  the  bit.  A  stepping  forward  usu- 
ally indicates  a  falling  out  of  the  outer  shoulder  and  must  be 
counteracted  by  the  outer  rein.  The  inner  rein  should  not  act 
so  strongly  as  to  bend  the  neck,  except  in  case  of  a  green  horse 
that  does  not  understand  the  leg  aids,  or  with  a  horse  that 
offers  resistance. 

The  turn  on  the  forehand  is  not  a  real  schooling  lesson,  be- 
cause the  haunches  are  disburdened  and  the  horse  thrown  on 
the  forehand.  For  this  reason  it  should  not  be  repeated  very 
often. 

As  a  rule,  turns  on  the  forehand  are  practiced  only  in  the 
early  training  of  the  horse.  Their  principal  purpose  is  to  teach 
the  rider  the  correct  use  of  the  sideward  driving  inner  leg  aid. 
the  inner  rein,  and  the  outer  supporting  leg  and  rein. 

As  the  movement  has  a  great  tendency  to  make  the  horse 
reluctant  in  going  up  promptly  against  the  bit,  the  turn  should 
be  always  immediately  followed  by  a  movement  to  the  front 
at  a  free  walk  or  at  a  trot,  and  it  should  never  be  exacted  of 
young  horses  until  the  straight-ahead  movement  has  been  well 
confirmed. 

TO    TURN    ON    THE    HAUNCHES 

50.  Being  in   line  or  column  at  the  halt :   1.  On  haunches,  2. 
To  the  right  (left),  or  2.  To  the  right  (left)  about,  3.  MARCH. 

The  rider  puts  his  horse  against  the  bit,  gathers  him,  and  sets 
the  head  to  the  side  of  the  turn.  The  inner  right  rein  begins 
and  induces  the  turn,  then  carried  well  away  from  the  neck, 


THE  SOLDIER  M  OCX  TED  101 

leads  the  forehand  step  by  step  around  the  haunches  through  a 
turn  of  90"  or  180",  respectively.  The  inner  right  hind  foot 
must  be  kept  in  place  during  the  turn.  To  accomplish  this,  the 
outer  rein  should  be  reined  in,  in  the  direction  toward  this  foot. 
The  outer  hind  foot  must  be  prevented  from  falling  out  by  the 
supporting  action  of  the  outer  leg.  Both  of  the  rider's  legs,  but 
especially  the  inner  one,  prevent  the  horse  from  stepping  back 
during  the  turn.  It  is  a  lesser  mistake  if  the  horse  steps  for- 
ward. The  rider  should  place  a  little  more  of  his  weight  on  the 
inner  buttock. 

The  instructor  must  see  that  the  rider's  legs  and  weight  are 
placed  as  above  described  and  that  the  tendency  to  let  the 
legs  fly  away  from  the  horse's  sides  be  completely  overcome. 


TO   TURN    ON    THE   FOREHAND   IN    REVERSE 

51.  Marching  on  the  track  to  either  hand:  1.  Rererse,  2. 
MARCH.  At  the  command  march  the  rider  leaves  the  track  by 
an  oblique.  Having  advanced  far  enough  in  this  direction  to 
place  him  from  6  to  15  yards  from  the  track,  the  instructor 
adds  NOW,  whereupon  the  rider  moves  his  horse  back  to  the 
track  over  the  arc  of  a  half  circle  whose  diameter  is  the  dis- 
tance thereto  and  retakes  the  track  in  the  opposite  direction. 

Application  of  the  aids. — At  the  moment  the  half  circle  is 
begun  the  aids  are  applied  and  the  horse  is  bent  as  if  to  march 
on  this  circle.  Immediately  thereafter  the  inside  leg  is  slipped 
in  rear  of  the  girth  to  the  sideward  driving  position  and  is 
applied  to  drive  the  haunches  outward  so  that  they  describe  an 
outer  and  larger  circle  than  the  forehand.  The  outer  leg  takes 
a  supporting  position  behind  the  girth  to  prevent  the  haunches 
from  coming  around  too  fast.  The  swing  of  the  haunches 
should  be  slight  as  the  half  circle  is  begun  and  should  then 
increase  as  the  track  is  approached.  The  lateral  drive  should 
be  strongest  when  the  forehand  has  almost  reached  the  track, 
and  the  haunches  are  about  1  yard  from  it. 

With  recruits  and  remounts  the  turn  should  be  made  on  a 
large  continuous  curve.  The  horse  is  therefore  changing  direc- 
tion while  gaining  ground  to  the  front.  The  diameter  of  the 
half  circle  described  by  the  forehand  is  never  less  than  6  yards. 

The  principal  object  of  this  movement  is  to  teach  the  horse 
to  yield  to  the  inside  aids,  especially  the  sideward  driving  leg-. 
It  is  therefore  of  great  value  to  teach  the  rider  the  co-ordina- 
tion and  use  of  these  aids  and  to  get  control  of  the  haunches 
of  his  horse 


102  MILITARY  SIGNAL  CORPS  MANUAL 

TO    REIN    BACK 

52.  Being  in  line  at  the  halt  :  1.  Backward,  2.  MARCH,  3. 
Squad,  4.  HALT. 

At  the  command  backward,  gather  the  horse. 

At  the  command  march,  keep  a  firm  seat,  hold  both  legs 
close;  carry  the  weight  of  the  body  slightly  to  the  rear,  and  at 
the  same  time  rein  in  gradually  until  the  horse  yields  to  the 
pressure  of  the  bit  and  steps  to  the  rear;  then  immediately 
yield  the  hand  slightly  to  allow  the  horse  to  regain  his  balance 
and  relax  the  legs ;  continue  in  the  same  manner  to  yield  the 
hand  and  relax  the  legs,  and  rein  in  and  close  the  legs,  giving 
slight  indication  to  the  rear  with  the  weight  of  the  body,  so 
as  to  keep  the  horse  in  continuous  motion. 

This  movement  should  be  frequently  practiced  to  keep  the 
horse  light  and  collected. 

If  the  horse  raises  his  nose  and  throws  his  weight  on  his 
haunches  without  stepping  back,  hold  the  hands  low  and  play 
the  reins  with  light,  rapid  motions  of  the  hands  until  he  yields. 

If  the  horse  throws  his  haunches  to  the  right,  close  well  the 
right  leg.  If  to  the  left,  close  well  the  left  leg.  If  this  be  not 
sufficient  to  put  the  horse  in  proper  position,  open  the  rein  on 
the  side  toward  which  he  throws  his  haunches,  supporting 
him  at  the  same  time  with  the  other  rein. 


TO    FORM    IN    LINE 

53.  To  form  in  line,  the  instructor  designates  a  trooper  to 
act  as  the  base  of  the  formation,  indicates  to  such  trooper 
the  point  where  the  right  &f  the  squad  is  to  rest  and  the 
direction  in  which  the  line  is  to  face,  takes  position  at  a  con- 
venient distance  in  front  of  and  facing  the  point  where  the 
center  of  the  squad  is  to  rest,  and  commands :  LEAD  INTO 
LINE.  The  base  trooper  lead^s  out  and  takes  position  as  in- 
dicated; the  other  troopers  lead  out  so  as  to  approach  the  line 
successively  directly  from  the  rear  and  in  single  rank  form  on 
the  line  established  by  the  base  trooper,  in  order  from  right 
to  left.  The  troopers  form  at  stand  to  horse,  with  intervals 
of  18  inches  between  horses. 

Line  having  thus  been  formed,  the  leader  commands  :  COUNT 
FOURS. 

At  this  command  all  except  the  right  or  base  trooper  turn 
the  head  and  eyes  to  the  right.  Beginning  on  the  right,  troop- 
ers count:  One,  two,  three,  four;  each  turning  his  head  and 
eyes  to  the  front  as  he  counts. 


THE  SOLDIER  MOUNTED 


103 


TO    MOUNT    IN     LINE 

54.  The  instructor  commands:  1.  Prepare  to  mount,  2. 
MOUNT,  3.  Form,  4.  RANK. 

At  the  first  command,  the  odd  numbers,  stepping  off  with 
the  left  foot,  lead  their  horses  4  yards  straight  to  the  front, 
regulating  by  the  right;  all  then  prepare  to  mount. 

At  the  command  mount,  all  mount. 

At  the  command   rank,  the  even  numbers  move  up  in  the  inter- 


432    1432    1 


vals  without  jostling  or  rushing.  In  forming  rank,  both 
mounted  and  dismounted,  the  odd  numbers  hold  their  horses' 
heads  well  up  to  prevent  kicking. 

TO     DISMOUNT 

55.  1.  Prepare  to  dismount,  2  DISMOUNT,  3.  Form,  4.  RANK. 
At  the  first  command,  the  odd  numbers  gather  their  horses 

and  move  forward  4  yards,  and   all  prepare  to  dismount. 

At  the  command  dismount,  all  dismount. 

At  the  command  rank,  the  even  numbers  move  up  in  the 
intervals. 

TO     MARCH     FROM     LINE    TO    THE    FLANK    IN     COLUMN    OF    FILES 

56.  Being  at  the  halt :  1.  By  file,  by  the  right  (left)  flank,  2. 
MARCH. 

At  the  first  command  the  man  on  the  right  gathers  his  horse. 

At  the  command  march,  he  turns  to  the  right  and  moves 
forward  in  the  new  direction.  The  second  man  from  the  tight 
gathers  his  horse  when  the  first  begins  to  move,  he  turns  to  the 
right  so  as  to  follow  the  first  at  the  distance  of  4  feet  from 


104 

head  to  croup.   The  movement  is  executed  in  succession  by  the 
other  men  as  explained  for  the  second. 

If  marching,  all  halt  at  the  command  inarch,  except  the  man 
on  the  right.  The  movement  is  then  executed  as  before. 

TO    MARCH    FROM    LINE    TO    THE    FRONT    IN    COLUMN    OF    FILES 

57.  Being  in  line  at  a  halt :  1.  By  file,  2.  MARCH.     Executed 
as  explained  above  for  marching  to  the  flank  except  that  the 
file  on  the  right  moves  straight  to  the  front,  followed  in  trace 
by  the  second  and  other  men. 

TO    PASS    FROM    THE    FRONT    TO    THE    REAR    OF    THE    COLUMN 

58.  Being  at  the  walk,  to  teach  the  troopers  the  application 
of  the   aids :    1.  First   man   from   front   to   rear,  2.  MARCH,  3. 
NEXT. 

At  the  first   command,  the   leading  man  gathers   his   horse. 

At  the  command  march,  he  leaves  the  column  by  the  right 
or  left  about,  according  as  he  is  marching  to  the  right  or  left 
hand,  moves  parallel  to  the  column,  and  enters  it  again  by  an- 
other about. 

The  men  in  succession  execute  the  same  movement  at  the 
command  next,  which  is  repeated  by  the  instructor  until  all 
the  men  have  passed  from  front  to  rear. 

TO    PASS    FROM    THE    REAR    TO    THE    FRONT    OF    THE    COLUMN 


59.  Being  at  the  walk  :  1.  Last  man  from  rear  to  front,  2.  Trot, 
3.  MARCH,  4.  NEXT. 

At  the  command  trot,  the  man  in  rear  gathers  his  horse. 

At  the  command  march,  he  leaves  the  column  by  an  oblique, 
takes  the  trot,  moves  parallel  to  the  column,  enters  it  again  at 
the  front  by  another  oblique,  and  resumes  the  walk,  and  so  on 
for  the  others,  each  moving  out  at  the  command  next. 

Should  the  man  enter  the  column  at  too  great  a  distance 
in  front  of  the  leading  trooper,  he  slackens  the  walk  until  at 
the  proper  distance. 

TO    MARCH    IN    CIRCLE 

60.  Marching  to  the  right,  and  the  conductor  being  at  least 
17  yards  from  a  corner  :  1.  Squad,  2.  Circle  to  the  right  (left), 
3.  MARCH. 

At  the  first  command,  the  conductor  gathers  his  horse. 


THE  SOLDIER  MOUNTED  105 

At  the  command  march,  he  describes  a  circle  between  the 
two  tracks;  the  other  men  follow,  each  gathering  his  horse 
before  entering  upon  the  circle,  keeping  him  there  by  the 
inner  rein,  and  closing  the  leg  on  that  side.  If  at  the  fast  trot 
or  gallop,  the  haunches  should  be  sustained  by  the  outside  leg. 

61.  While  circling,  the  squad  may  change  gaits,  be  halted 
in  column,  and  put  in  march,  as  when  marching  on  the  track. 

To   change   hands:   1.  Column  right   (left),  2.  MARCH. 

The  squad  passes  over  the  diameter  of  the  circle  and  circles 
in  the  opposite  direction  by  the  commands :  3.  Column  left 
(right),  MARCH,  the  command  march  being  given  when  the 
conductor  is  2  yards  from  the  circumference. 

To  march  again  on  a  straight  line,  the  instructor  commands  : 
1.  Forward,  2.  MARCH,  when  the  conductor  arrives  on  the 
long  side  of  the  track. 


INDIVIDUAL   CIRCLING 

62.  Marching  to  the  right  (left)  hand  on  the  long  side  ol 
the  hall :  1.  Individual,  circle  to  the  right  (left),  2.  MARCH. 

The  men  should  make  one  circle  only,  should  complete  it  at 
the  same  time,  and  take  the  track  to  the  same  hand  as  when 
the  movement  began.  The  instructor  should  make  the  circle 
larger  in  the  beginning,  and  as  the  instruction  progresses 
make  it  smaller. 

When  marching  on  the  circle  to  the  right,  each  man  opens 
the  right  rein  and  closes  both  legs ;  when  marching  at  the  trot 
or  gallop,  he  closes  the  left  more  than  the  right,  to  sustain 
the  horse. 


L.  


If  the  commands  :  1.  Squad,  2.  HALT,  be  given,  the  men  halt 
their  horses  facing  in  the  same  direction  as  the  conductor. 


106  MILITARY  SIGNAL  CORPS  MANUAL 

TO    MOVE   AT  THE    SLOW    TROT 

63.  1.   Slow   trot,  2.   MARCH. 

The  gait  is  slow,  and  the  instructor  sees  that  the  men  feel 
lightly  their  horses'  mouths  without  bearing  upon  the  reins, 
and  explains  that  the  necessary  ease  and  stability  are  acquired 
by  sitting  well  down  on  the  horse,  or  saddle;  and  partially 
relaxing  the  body,  thighs,  and  legs,  the  hands  feeling  lightly  the 
horse's  mouth. 

He  requires  the  men  to  preserve  their  seats  by  balancing 
the  body;  that  they  avoid  the  common  fault  of  leaning  the 
body  too  far  or  curving  the  back  to  the  rear;  that  they  sit 
erect  and  keep  the  legs  close  to  the  horse. 

The  movements  already  taught  at  the  walk  are  repeated  at 
the  trot.  In  turning  by  file  to  the  right  or  left,  the  instructor 
sees  that  the  trot  is  neither  slackened  nor  increased. 

TO    TROT    OUT     - 

64.  Being  at  the  slow  trot :  1.  Trot  out,  2.  MARCH. 

Gather  the  horse,  then  yield  the  hands  and  close  the  legs  by 
degrees  until  the  horse  gradually  increases  the  gait  to  the  trot. 

The  instructor  sees  that  the  horses  are  kept  up  to  the  proper 
gait  and  pays  particular  attention  to  the  position  of  the  men  ; 
if  their  seats  become  too  much  deranged,  he  brings  the  squad 
to  the  slow  trot  or  to  the  walk;  this  is  especially  important 
in  the  earlier  instruction  of  recruits. 

65.  To  resume  a  moderate  trot:  1.  Slow  trot,  2.  MARCH. 
Rein  in  by  degrees  until  the  horse  moderates  the  gait,  clos- 
ing the  legs  to  prevent   his   taking  the  walk. 

The  greater  part  of  the  work  without  saddles  or  stirrups 
should  be  given  at  the  slow  trot,  as  it  is  unnecessarily  fatiguing 
and  difficult  to  sit  at  a  fast  trot  without  the  saddle  or  stirrups. 

66.  In    riding   at   a   slow   trot,   those   undergoing   instruction 
will  "sit  tight  in  the  saddle,"  i.  e.,  maintain  contact  therewith 
with  the  buttocks.     In  riding  at  the  regulation  trot  it  is  pre- 
scribed that  posting  or  rising  to  the   trot,  as  hereinafter  ex- 
plained, be   employed. 


67.  Posting,  or  rising  to  the  trot,  greatly  diminishes  the 
concussion  produced  by  the  rider's  weight  on  the  back  and 
joints  of  the  horse.  It  also  makes  breathing  easier  and  facili- 
tates the  impulsion  from  the  engagement  of  the  hind  feet.  It 
is  also  less  fatiguing  to  the  rider  than  sitting  down  to  the 
trot. 


THE  SOLDIER  MOl'\'TED  107 

Posting  is  habitually  employed  by  the  rider,  and  should  be 
learned  during  this  period  of  the  instruction. 

It  is  executed  as  follows  :  The  horse  moving  at  a  trot,  the 
rider  inclines  the  upper  part  of  his  body  forward,  then  sup- 
porting himself  on  the  stirrups  while  maintaining  the  grip  of 
the  knees,  he  rises  under  the  impulsion  of  the  horse,  maintain- 
ing his  position  detached  from  the  saddle  while  the  succeeding 
impulse  is  produced,  again  sits  down  in  the  saddle,  shoving 
his  buttocks  forward  in  doing  so,  and  continues  in  this  way, 
always  avoiding  every  other  impulse. 

At  the  beginning  the  mechanism  of  posting  is  made  easier  to 
the  rider  by  causing  him  to  stroke  the  horse's  neck  or  to  grasp 
a  lock  of  the  mane  or  the  pommel  with  either  hand,  thus 
determining  the  forward  inclination  of  the  body. 

Its  proper  execution  requires  that  the  seat  shall  be  raised 
moderately;  that  contact  with  the  saddle  shall  be  resumed 
gently  and  without  shock;  that  the  full  support  of  the  stirrup 
is  obtained,  while  keeping  the  lower  leg  steady;  that  the  ankle 
joint  shall  be  supple;  and  that  the  heel  shall  be  kept  lower 
than  the  toe.  Above  all,  the  rider  must  be  supple  in  the  loins 
and  convex  them  backward. 

CHANGING   THC    DIAGONAL    IN    POSTING 

68.  In  posting  the  rider  is  said  to  post  on  the  right  diagonal 
when  after  rising  he  sits  down  in  the  saddle  at  the  instant 
the  right  fore  foot  comes  to  the  ground. 

It  is  important  to  instruct  the  rider  to  post  for  a  time  on 
one  diagonal  and  then  change  to  the  other,  so  that  the  horse's 
legs  will  each  perform  the  same  amount  of  work  and  the  chance 
of  injury  from  the  equipment  will  be  reduced. 

In  the  riding  school  the  rider  should  always  ride  on  the 
inside  hind  foot,  because  this  foot,  in  response  to  the  inner  leg 
aid,  is  the  only  one  that  can  properly  place  itself  under  the 
mass  of  the  horse  and  support  the  weight  during  the  change  of 
direction  in  the  corners;  hence  to  insure  automatically  that 
the  posting  is  done  as  much  on  one  diagonal  as  on  the  other 
the  riders  may  be  required  to  post  on  the  left  diagonal  when 
riding  to  the  right  hand  on  the  track  and  on  the  right  diagonal 
when  riding  to  the  left. 

The  instructor  occasionally  requires  each  rider  to  inform  him 
on  which  diagonal  he  is  posting. 

To  teach  the  rider  to  change,  the  diagonal,  the  instructor 
directs  him  to  diminish  the  weight  borne  on  the  stirrups  and 
to  retain  his  seat  in  the  saddle  for  two  successive  beats  of  the 
horse's  feet  instead  of  one,  and  then  to  rise  as  before. 

The  rider  will  then  find  himself  posting  on  the  diagonal 
opposite  to  the  one  on  which  he  was  posting  before. 


108  MILITARY  SIGNAL  CORPS  MANUAL 

TO   GALLOP 

69.     1.  To  3  yards  take  distance,  2.  TROT,  3.  MARCH. 

The  leading  man  takes  the  trot;  each  of  the  other  men  in 
succession  takes  the  trot  when  the  one  in  front  of  him  has 
gained  the  distance  of  3  yards. 

This  precaution  is  taken  to  prevent  the  horses  running  upon 
each  other  and  causing  confusion. 

1.  Gallop;    or,  canter,  2.  MARCH. 

At  the  command  gallop,  gather  the  horse. 

At  the  command  march,  close  both  legs  and  rein  in  with  a 
firm,  light  hand  (this  is  to  bring  the  haunches  under),  then 
carry  the  bridle  hand  to  the  left  and  press  the  left  leg  with 
vigor;  these  actions  throw  the  weight  on  the  near  hind  leg  and 
allow  the  off  fore  and  hind  feet  to  lead;  as  soon  as  the  horse 
rises,  give  the  hand  and  relax  the  left  leg;  reining  in  slightly 
and  closing  the  legs  with  light  pressure  will  keep  the  horse  at 
the  gait  and  up  to  the  hand;  a  dead  pull  should  be  avoided;  if 
the  horse  leans  on  the  hand,  yield  the  hand  and  play  the  reins 
a  little,  then  close  the  legs  and  rein  in  a  little  abruptly;  as 
soon  as  the  horse  obeys,  yield  the  hand. 

For  recruits  the  gait    at    first    is    restricted   to   the    canter. 

To  keep  the  horse  true  the  rider  must  accommodate  himself 
to  all  the  horse's  motions,  sustaining  him  slightly  with  the 
outside  leg,  particularly  in  changing  direction  at  the  corners. 
When  a  horse  gallops  false  or  disunited,  his  rider  is  ordered 
to  leave  the  column,  come  to  the  trot,  and  pass  to  the  rear  of 
the  column,  taking  care  not  to  interfere  with  the  other  men ; 
arriving  at  the  rear  he  resumes  the  gallop,  the  instructor  ex- 
plaining how  to  keep  the  horse  true.  The  gallop  to  each  hand 
will  be  kept  up  only  once  or  twice  around  the  riding  school, 
the  horses  being  brought  to  the  trot  before  changing  hands. 

In  turning  corners  at  a  fast  gait  there  is  danger  that  the 
horse  will  fall  down.  If  his  haunches  swing  out,  he  will  change 
so  as  to  gallop  disunited,  and  the  danger  of  his  falling  will  be 
increased.  To  prevent  this  the  man  should  keep  the  outside  leg 
closed  strongly  and  not  lean  in,  but  maintain  a  vertical  posi- 
tion. 

The  instructor  will  not  at  first  dwell  upon  the  mechanism  of 
the  gait,  but  allow  each  rider  to  accommodate  himself  to  the 
motion  of  the  horse  without  losing  his  seat. 

The  men  must  keep  their  horses  steady;  when  able  to  man- 
age them  properly  at  the  gallop  the  distance  of  4  feet  from 
head  to  croup  is  gradually  resumed. 

In  order  to  make  it  easier  for  each  man  to  start  his  horse 
true,  the  instructor  will  find  it  advantageous  to  march  the  squad 


THE  SOLDIER  MOUNTED  109 

in  line  with  intervals  across  the  hall  at  the  trot,  and,  upon 
approaching  the  track,  command:  1.  By  the  right  flank,  2. 
Gallop;  or,  2.  Canter,  3.  MARCH. 

Or,  give  the  command  gallop  or  canter  wrfen  the  squad  is 
circling  at  the  trot. 

When  the  men  have  been  sufficiently  exercised  at  the  gallop 
on  straight  lines  and  in  circling,  they  are  exercised  at  the 
gallop  in  marching  by  the  flank  and  circling  by  man,  the  in- 
structor taking  care  that  the  turns  are  not  made  too  short ; 
that  the  men  keep  their  horses  true,  and  that  they  do  not  de- 
range their  positions. 

TO    PASS    FROM    THE    CANTER    TO   THE    GALLOP,   AND    THE   REVERSE 

70.  Being  at  the  canter :  1.  Gallop,  2,  MARCH. 

Give  the  hand  and  close  the  legs  by  degrees  until  the  horse 
increases  his  gait  to  the  gallop;  when  the  proper  cadence  is 
attained,  the  instructor  pays  particular  attention  to  the  posi- 
tions of  the  men ;  if  their  seats  become  too  much  deranged,  he 
brings  the  squad  to  the  canter  or  to  the  trot. 

To  resume  the  canter :  1.  Canter,  2.  MARCH. 

Rein  in  by  degrees  until  the  horse  moderates  the  cadence, 
closing  the  legs  to  prevent  his  taking  the  trot. 

TO    PASS    FROM     THE    GALLOP    OR    CANTER    TO    THE   TROT 

71.  1.  Trot,  2.  MARCH. 

At  the  command  trot,  gather  the  horse. 

At  the  command  march,  rein  by  degrees  and  hold  the  legs 
close;  as  soon  as  the  horse  trots  replace  the  hand  gradually 
and  relax  the  legs. 

JUMPING 

72.  For  this  exercise  the  height  of  the  bar  should  at  first 
be  1  foot,  and  the  width  of  the  ditch  2  feet.    As  the  men  and 
horses  become  used  to  jumping,  the  height  of  the  bar  and  the 
width  of  the  ditch  are  gradually  increased,  the  bar  to  3  feet 
and  the  ditch  to  5  feet ;  this  exercise  should  generally  be  prac- 
ticed near  the  end  of  each  drill. 

A  horse  that  hurries  or  rushes  will  become  an  uncertain  and 
unsafe  jumper.  If  impatient  in  going  up  to  the  bar,  he  should 
be  halted,  reined  back,  halted  and  tried  again  until  he  takes 
it  coolly. 

73.  Horses  are  taught  to  jump  the  ditch  and  the  bar.     They 
are  equipped  with  the  snaffle  bit  and  are  led  by  a  steady  horse 
that  is  accustomed  to  jumping. 

This  instruction  is  also  given  on  the  longe. 


110  MILITARY  SIGXAL  CORPS  MANUAL 

The  horses  are  taken  in  the  open  field  and  practiced  at 
jumping  shallow  ditches,  fallen  logs,  very  low  fences,  etc.  If 
the  horse  refuses  to  take  the  jump,  the  instructor  may  give  aid 
with  the  whip,  but  in  such  a  way  as  not  to  terrify  him.  If  the 
horse  be  timid,  it  is  advisable  to  place  the  bar  on  the  ground 
until  he  passes  over  it  without  alarm.  Great  discretion  must 
be  used  in  applying  the  whip,  and  the  horses  will  not  be  re- 
quired to  jump  repeatedly  over  the  same  thing  or  at  the 
same  place. 

74.  The  instructor  forms   the   squad  in   line,  about  30  yards 
from  the  obstacle,  and  commands  :  1.  First  file  from  the  right 
(left),  2.  MARCH,  3.   NEXT. 

The  man  on  the  right  moves  to  the  front  at  the  walk;  he 
takes  the  trot  when  he  has  passed  over  about  one-third  the 
distance,  and  then  the  gallop. 

After  making  the  jump,  he  takes  the  trot,  then  the  walk,  and 
takes  his  place  in  the  rank,  which  is  re-formed  about  30  yards 
beyond,  and  on  the  right  or  left  of  the  obstacle,  and  facing  it. 

The  other  men  move  out  successively  from  the  right  at  the 
command  NEXT. 

75.  In   the   riding  hall  the  men   are  formed  in   two  squads, 
in   line,  facing  each   other  at   opposite  ends   of  the  hall;  two 
bars  are  placed  across  the  track,  one  on  each  of  the  long  sides 
of  the  hall,  about  midway. 

1.  First  file  from  the  right  (left),  2.  MARCH,  3.  NEXT. 

The  man  on  the  right  of  each  squad  moves  out  at  the  walk 
and  marches  diagonally  across  the  hall;  on  passing  each  other 
both  take  the  trot  and  when  abreast  of  the  flank  of  the  op- 
posite squad  they  take  the  track  at  the  gallop  or  canter,  the 
horse  leading  with  the  right  foot;  after  jumping  both  bars, 
each  man  takes  the  trot,  then  the  walk,  passes  around  the  left 
flank  of  the  opposite  squad,  marches  at  the  walk  diagonally 
across  the  hall,  and  forms  on  the  left  of  his  squad. 

76.  The  other  men  move  out  successively  from  the  right  or 
left  of  each  squad  at  the  command  NEXT. 

This  rule  is  general  for  individual  exercises. 

77.  In  making  the  flying  jump,  the  horse  must  not  be  hur- 
ried nor  allowed  to  rush,  but  be  held  steady  and  straight  for 
the  bar  or  other  obstacle.     The  rider  should  sit  down  snugly 
in  the  middle  of  his  saddle,  the  horse  firmly  inclosed  between 
the  legs,  the  hands  held  low  and  steady,  and  the  body  not  for- 
ward,  and    thus    ride    steadily    and    smoothly    at    the    obstacle. 
The   muscles   of   the   back   and   shoulders   should   not   be   con- 
tracted.    The   waist   should   be    supple,   so   as   to   adopt   in  its 
motion  the  movement  of  the  horse. 


THE  SOLDIEK  MOUNTED  111 

TO    JUMP    THE    DITCH 

78.  Ride  straight  for  the  ditch  at  a  steady,  animated  gait, 
with  the  legs  closed  firmly;  the  instant  the  horse  springs,  give 
the  hand,  and  as  he  grounds  sustain  him  with  a  light,  steady 
pressure. 

79.  The  instructor  must  observe  that  the  rider  does  not 
thrust  his  weight  into  the  stirrups  nor  throw  out  his  elbows, 
nor  check  his  horse  too  abruptly.  If  the  hand  is  held  so  that 
the  back  of  the  hand  is  nearly  vertical  with  the  ground,  there 
will  be  little  tendency  to  turn  out  the  elbows.  If  the  horse  i» 
checked  with  a  sudden  violence  after  making  the  jump,  he  takes 
it  as  a  punishment,  and  may  thereafter  try  to  avoid  the 
obstacle. 

Beginners  are  apt  to  try  to  sustain  themselves  by  the  reins ; 
to  prevent  this  the  instructor  may  find  it  necessary  to  allow 
them  to  place  the  bridle  hand  on  the  horse's  neck  until  they 
have  gained  confidence.  If  necessary  the  bar  should  be  lowered 
to  the  height  at  which  the  rider  can  easily  keep  his  seat. 

The  rider  will  be  practiced  jumping  obstacles  without  stir- 
rups and  without  saddles. 


ELEMENTARY    COLLECTIVE    MOUNTED  INSTRUCTION 

ALIGNMENTS 

80.  Being   in    line,   mounted:    1.   Right    (left),   2.   DRESS,   3. 
FRONT. 

At  the  command  dress  all  the  men  move  up  slowly  on  the 
basis  of  the  alignment  established  by  the  instructor,  each  casts 
his  eyes  to  the  right  so  as  to  see  the  buttons  on  the  breast  of 
the  second  man  from  him,  sits  squarely  on  his  horse,  keeps  his 
horse  straight  in  ranks,  and  touches  lightly  with  his  stirrup  the 
stirrup  of  the  man  on  his  right.  At  the  command  front,  given 
with  the  last  man  is  aligned,  all  cast  their  eyes  to  the  front. 
All  movements  in  ranks  must  then  cease. 

In  dressing  the  first  two  or  three  men  are  accurately  aligned 
as  quickly  as  possible,  in  order  to  afford  a  base  for  the  rest  of 
the  squad. 

This  rule  is   general. 

TO    MARCH    IN    LINE 

81.  Being  in  line  at  the  halt :     1-  Forward,  2.  MARCH.     The 

squad  moves  off  promptly,  the  guide  marching  straight  to  the 
front  at  the  regular  gait. 

The  instructor  observes  in  marching  in  line  that  the  squad 
marches  straight  to  the  front  at  the  regular  gait ;  that  the  men 
keep  their  horses  straight  in  the  rank;  that  they  maintain  the 
interval  of  about  6  inches  from  knee  to  knee  or  light  touch 
with  stirrup  toward  the  side  of  the  guide;  that  they  yield  to 
pressure  from  that  side  and  resist  pressure  from  the  opposite 
direction ;  that  if  too  much  closed  toward  the  guide  they  carry 
the  bridle  hand  from  that  side,  and  close  the  leg  on  the  side  of 
the  guide;  that  if  the  interval  be  too  great  they  carry  the  band 
toward  the  guide,  and  also  close  the  leg  on  the  opposite  side, 
and,  while  habitually  keeping  the  head  to  the  front,  they  occa- 

112 


COLLECTIVE    MOl'XTJ'l)    INSTRUCTION  11.1 

sionally  glance  toward  the  guide.  If  in  advance,  they  rein  in 
gradually.  If  in  rear,  they  gradually  increase  the  gait  until 
the  alignment  is  regained. 

82.  Marching  in  line,  to  effect  a  slight  change  of  direction: 
INCLINE  TO  THE  RIGHT  (LEFT). 

The  guide  turns  his  horse  slightly  to  the  right  and  marches 
in  the  new  direction.  The  other  men  gradually  conform  to  the 
movements  of  the  guide,  increasing  or  diminishing  the  gait 
according  as  the  change  is  toward  or  opposite  the  side  of  the 
guide. 

TO    HALT 

83.  Whenever   the   squad   is   in   motion,   it   is   halted  by  the 
commands:  1.  Squad,  2.  HALT.     This  rule  is  general,  the  com- 
mand   section,   platoon,   company,   being   substituted   for   squad. 

TO    MARCH    BACKWARD 

84.  1.   Backward,  2.   MARCH. 

All  the  men  rein  back,  dressing  on  the  guide. 
This  movement  is  used  for  short  distances  only. 


TO  OBLIQUE 

85.  1.  Right  (left)  oblique,  2.  MARCH. 

At  the  command  march  each  man  executes  a  turn  of  45° 
to  the  right,  his  right  knee  in  rear  of  the  left  knee  of  the  man 
on  his  right.  The  squad  moves  in  the  new  direction,  regulat- 
ing by  the  right,  in  a  line  parallel  to  the  original  front. 

To   resume  the   original  direction:   1.  Forward,  2.   MARCH. 

Each  man  turns  45°  to  the  left  and  marches  straight  to  the 
front,  regulating  on  the  guide. 

TO    TURN    AND    ADVANCE 

86.  Being  in  line  at  the  halt  or  at   the   walk,  the   instructor 


114  MILITARY  S1CX.I1.  COIN'S  .U./ATJL 

commands  :  1.  Right  (left)  turn,  2.  MARCH.     The  man   on  the 

right  turns  his  horse  90°  to  the  right,  on  an  arc  with  a  radius 
of  2  yards,  and  moves  forward  in  the  new  direction  without 
increasing  the  speed.  Each  of  the  other  men  turns  his  horse  to 
the  right  aproximating  an  oblique,  and,  moving  at  the  trot 
by  the  shortest  line,  places  himself  on  the  new  line,  when 
he  takes  the  gait  and  direction  of  the  pivot  man.  During  the 
turn  the  guide  is,  without  command,  on  the  pivot  flank.  The 
guide  is  announced  when  all  men  have  arrived  on  the  line.  If 
marching  at  a  trot,  the  pivot  man  continues  at  the  trot.  All 
others  move  at  the  gallop.  If  marching  at  the  gallop,  the  pivot 
takes  the  canter;  all  other  men  continue  .jihe  gallop,  each 
taking  the  canter  on  arriving  in  line ;  as  soon  as  all  the  men 
have  arrived  on  the  line  all  resume  the  gallop. 

BEIXG     IX     LINE    AND    HAVING    COUNTED    FOURS,    TO    FORM     COLUMX     OF, 
FOURS   TO   THE   FROXT 

87.  1.  Right  (left)  by  fours,  2,  MARCH.   The  right  four  moves 
straight  to  the  front,  the  other  fours  oblique   to  the   right,  so 
as   to   follow   the   preceding  four   at   the   proper   distance   of  4 
feet  from  head  to  croup. 

If  marching,  rule  2,  paragraph   133,  applies   for  gaits. 

REING    IN     LINE    AND     HAVING    COUNTED    FOURS,     TO     FORM     COLUMN     OF 
FOURS    TO    THK    FLANK 

88.  1.  Four*  right  (left),  2.  MARCH. 

Each    four    executes    RIGHT    TURN,  as    explained    in    para- 
graph 86,  and  all  march  off  in  the  new  direction. 

TO    CHANGE    DIRECTION" 

89.  Being  in  columns  of  fours  :  1.  Column  right,  2.  MARCH. 

The  leading  four  executes  right  turn,  the  other  fours  move  for- 
ward and  turn  on  the  same  ground  as  the  first.  Column  half 
right  is  similarly  executed,  except  that  the  leading  four  makes 
a  half  turn. 

BEING    IN    COLUMN    OF    FOURS,    TO    MOVE    TO    THE    REAR 

90.  1.  Right  about,  2.  MARCH.     The   leading  four  turns   to 
right    about,    the    pivot    trooper    marching   on    a    circle    whose 
radius    is   2   yards,    the    others    conforming.     The    other    fours 
move    forward,    and,    following    the    first,    turn    on    the    same 
ground. 


COLLECTIVE   MOl'XTHD   INSTRUCTION  115 

BK1XG    IX    COLUMN    OK    FOURS,    TO    FORM    LINE    TO    THE    FRONT 

91.  1.   Left    (Right)    front   into    line,  2.   MARCH.     The    lead- 
ing four   moves   straight   to  the  front,  each   of   the   rear  fours 
obliques  to  the  left  until  the  preceding  four  is  uncovered,  when 
it  moves  straight  to  the  front  until  it  arrives  on  the  line. 

Rule   1,  paragraph   133,  applies  for  gaits. 

BEING   IN   COLUMN   OK  FOURS,   TO   FORM    COLUMN   OF   TWOS   TO  THE   FRONT 

92.  Being  at  a  halt :  1.  By  twos,  2.  MARCH. 

The  right  two,  Nos.  1  and  '2  of  the  leading  four,  moves 
straight  to  the  front,  the  left  two,  Nos.  3  and  4  of  the  leading 
four,  keep  their  horses'  heads  straight  until  their  horses'  heads 
are  passed  by  the  croups  of  the  horses  of  the  right  two,  when 
they  oblique  to  the  right  and  follow  the  leading  two,  at  a  dis- 
tance of  4  feet.  Each  of  the  other  fours  form  in  the  same  man- 
ner as  soon  as  the  left  two  in  the  preceding  four  commences  to 
oblique.  Nos.  3  and  4  always  follow  in  rear  of  Nos.  1  and  2, 
no  matter  on  which  side  the  guide  may  be. 

If  marching,  Rule  2,  paragraph  133,  applies  for  gaits. 

1U-.1XG    IN    COLUMN    OK    FOURS,    TO    FORM    COLUMN    OK    FILES 

93.  1.  By  file,  2.  MARCH. 

The  movement  is  executed  according  to  the  principle?  of  the 
preceding  paragraph.  No.  1  of  the  leading  four  moves  forward 
and  is  followed  successively  by  Nos.  2,  3,  and  4,  who  preserve  a 
distance  of  4  feet  from  head  to  croup.  When  No.  4  commences 
to  oblique,  No.  1  of  the  succeeding  four  marches  forward  or 
takes  the  increased  gait. 

Column  of  files  from  column  of  twos  is  formed  in  similar 
manner,  No.  1  leading  the  column. 

BEING    IN  COLUMN    OK    TWOS,    TO    FORM    COLUMN    OF    FOURS 

94.  Being  at   the   halt:   1.   Form   fours,  2.   MARCH.     Nos.    1 
and  2   of   the    leading   four    move    straight    to   the    front.     The 
instructor  commands  halt  when  the  leading  two  have  moved  3 
yards.     Nos.  3   and  4  of   the   leading  four   oblique   to   the   left 
until  uncovered,  then  march  to  the  front  and  halt  when  abreast 
of   Nos.    1    and  2.     The   other    twos   march,  forward   and   form 
fours  successively  as  explained  for  the  first   four.     Xos.  3  and 
4  of  each   four  commence   the  oblique   to  the   left  when   Nos.   1 
and  2  are  at  3  yards  from  their  position. 

If  marching,  rule  1,  paragraph  133,  governs   the  gaits. 


116  MILITARY  SIGNAL  CORPS  MANUAL 

BEING   IN    COLUMN    OF    KII.ES,   TO   FORM    COLUMN    OF   FOURS    OR   TUoS 

95.  1.  Form  fours,  2.  MARCH. 

The  movement  is  executed  on  the  same  principles  as  in  form- 
ing' fours  from  column  of  twos,  No.  1  of  each  four  being  the 
base,  and  Nos.  2,  3,  and  4  obliquing  to  the  left  and  forming  on 
the  left  of  No.  1. 

96.  1.  Form  twos,  2  MARCH.    The  movement  is  executed  on 
the   same   principles    as    in    forming   fours,   Nos.    1    and   3   being 
the  base  men,  No.  2  forming  on  the  left  of  No.  1,  and  No.  4  on 
the  left  of  No.  3. 

MOVKMKNTS    IN    COLUMN    OF    TWOS 

97.  The   column   of   twos    changes    direction,   halts,   and    ad- 
vances by  the  same  commands  and  means  as  a  column  of  fours. 

B'vTNG    IN     COLUMN     OF     FOURS,    TO    DISMOUNT 

98.  Being  at   the  halt  or  marching:   1.  Prepare  to  dismount, 
2.  DISMOUNT. 

At  the  first  command,  Nos.  1  and  2  open  to  the  right  and 
front,  Nos.  3  and  4  to  the  left  and  front,  and  all  halt.  Each 
four  opens  only  so  far  as  to  allow  sufficient  room  for  each  man 
to  dismount  without  interference  from  the  others.  Nos.  1  and 
4  open  a  little  more  than  2  and  3. 

The  column  of  twos  dismounts  by  the  same  commands  and 
means.  In  mounting  from  column  of  twos  or  fours  the  horses 
are  opened  out  as  in  the  preceding  paragraph  at  the  prepara- 
tory command  for  mounting.  At  the  commands  Forward, 
March,  either  before  or  after  mounting,  the  column  moves  for- 
ward, the  files  closing  toward  the  center. 

MANUAL    OF    THE     PISTOL 

99.  The    instruction    under   this    head   will   conform   to   what 
has  already  been  described  in  The  Soldier  Dismounted. 


FIELD  SIGNAL  TROOPS 

OBJECT  AND  COMPOSITION 

Field  signal  troops  comprise  those  Signal  Corps  units  per- 
manently assigned  to  divisions,  army  corps,  and  armies  for 
the  purposes  of  establishing  and  maintaining  tactical  lines  of 
information  and  for  transmitting  over  these  lines  such  informa- 
tion as  is  incident  to  operations  in  the  field. 

The  basis  of  organization  for  field  signal  troops  is  the 
field  battalion,  which  is  composed  of  a  headquarters  and  a  sup- 
ply detachment,  a  wire  company,  a  radio  company,  and  an 
outpost  company. 

One  field  battalion  is  assigned  to  each  division,  one  to  each 
army  corps,  and  such  number  as  necessary  to  each  army. 

Field  signal  troops  assigned  to  a  division  are  used  only  in 
the  presence  of  an  enemy,  real  or  assumed.  Their  use  in  the 
handling  of  routine  and  administrative  matters  or  for  the  con- 
venience of  the  personnel  of  the  division  is  unauthorized  ex> 
cept  in  so  far  as  these  are  related  to  existing  tactical  situations. 

Field  signal  troops  assigned  to  army  corps  and  armies 
are  intended  to  furnish  a  reserve  for  the  field  battalions  in 
advance,  to  supplement  the  work  of  the  latter  when  necessary 
or  desirable,  and  for  use  with  separate  brigades  and  expedition- 
ary forces.  In  emergency,  these  troops  may  assist  telegraph 
troops  in  establishing  and  maintaining  the  necessary  strategical 
lines  of  information. 

The  normal  use  of  field  signal  troops  is  to  establish,  main- 
tain, and  operate  tactical  lines  of  information  within  the 
division  and  such  is  the  use  which  will  be  dealt  with  herein- 
after. Field  signal  troops  assigned  to  army  corps  and  armies 
normally  constitute  a  reserve  and,  except  for  the  use  of  wagon 
radio  sets  for  communicating  with  divisions,  their  active  em- 
ployment otherwise  is  to  be  regarded  as  exceptional. 

117 


THE  WIRE  COMPANY 

FUNCTION    AND    EMPLOYM  KNT 

100.  The  wire  company  is  the  field  signal  organization  used 
by  the  commander  of  a  division  for  establishing  and  maintain- 
ing   those    tactical    lines    of    information    which    radiate    from 
division  headquarters,  and  which  serve,  in  general,  to  connect 
these    headquarters    with    the    major    subordinate    units.      Nor- 
mally the  wire  company  is  used  to  connect  division  headquart- 
ers with  the  headquarters  of  the   various  brigades  within  the 
division,  with  the  divisional  artillery,  and,  in  some  cases,  with 
the   divisional   trains.     Opportunity   for   its   use  in   maintaining 
communication  with  the  divisional  cavalry  will  occur  so  rarely 
that    its    employment    in    this    manner    is    prohibited    except    in 
emergency. 

ORGANIZATION 

101.  The  wire  company  is  organized  into  the  necessary  head- 
quarters and  company  staff  and  two  platoons  of  two  wire  sec- 
tions each. 

For  drill  the  company  is  formed  as  above.  In  the  field  or  on 
the  march  the  company  instrument  wagon  and  the  two  reserve 
wire  carts  form  a  third  platoon  under  command  of  the  supply 
sergeant. 

102.  The  organization,  in  detail,  is  as  follows: 

1  captain.  2  cooks. 

2  first  lieutenants.  1   farrier   (corporal). 
1  master  signal  electrician.                1  saddler   (corporal). 

1  first  sergeant  (sergeant,  first  1  mechanic  (corporal). 

class).  1  assistant  mechanic  (private 
1  supply  sergeant  (sergeant).  first  class. 

1  stable  sergeant  (sergeant).  3  drivers  (private,  first  class). 

1  mess   sergeant    (sergeant).  1  guidon   (private,  first  class). 

1  horseshoer.  2  buglers  (privates,  first  class). 

1  clerk  (corporal).  4  wire  sections. 

118 


THE  WIRE  COMPANY  119 

DUTIES    OF    INDIVIDUALS 

The  captain  commands  the  company  and  is  responsible  for 
its  training  and  efficiency. 

The  lieutenants  command  platoons,  and  will  be  assigned  to 
such  other  duties  as  the  captain  may  deem  necessary. 

The  master  signal  electrician  is  responsible  to  the  captain 
for  the  condition  of  the  technical  equipment  of  the  company. 
To  this  end  he  will  make  frequent  and  regular  inspections  of 
same  and,  when  parts  of  the  technical  equipment  are  found 
or  reported  unserviceable,  will  make  or  supervise  the  necessary 
adjustments  or  repairs.  Under  the  direction  of  the  captain,  he 
will  order  such  precautionary  and  corrective  measures  as  he 
may  deem  advisable  concerning  the  care  and  repair  of  technical 
equipment.  Master  signal  electricians  also  act  as  substitute 
chiefs  of  platoons. 

The  first  sergeant  is  the  assistant  of  the  captain,  and  is  re- 
sponsible to  him  for  the  general  good  order,  police,  and  dis- 
cipline of  the  company.  In  action  he  remains  with  the  captain 
and  under  his  immediate  orders. 

The  supply  sergeant  is  responsible  to  the  captain  for  the 
care  and  preservation  of  the  material  not  issued  to  the  sections. 

The  stable  sergeant  is  responsible  to  the  captain  for  the  gen- 
eral care  of  the  public  animals  assigned  to  the  company,  the 
good  order  and  police  of  the  stables  and  picket  lines,  and  the 
conduct  of  the  stable  personnel,  when  on  duty. 

The  mess  sergeant  is  responsible  to  the  captain  for  the  effici- 
ent and  economical  handling  of  the  ration,  for  the  conduct  of 
the  kitchen  personnel  when  on  duty  and  for  the  cleanliness  of 
the  company  kitchen  and  surroundings. 

The  mechanics,  under  the  orders  of  the  supply  sergeant,  are 
responsible  for  the  repair  of  the  material  pertaining  to  the 
company 

Chiefs  of  sections  command  the  sections  and  will  bxe  held 
responsible  to  the  captain  for  the  condition  of  their  equipment 
and  the  training  and  efficiency  of  their  sections.  They  will 
make,  or  cause  to  be  made,  such  minor  adjustments  or  repairs 
to  technical  equipment  as  can  be  effected  by  the  personnel  ot 
the  section,  promptly  reporting  more  serious  deficiencies  to 
the  master  signal  electrician. 

The  drivers  are  directly  responsible  to  their  chiefs  of  sec- 
tions for  their  animals,  harness,  and  equipment.  They  will 
report  at  once  to  their  chief  of  section  any  injury  to  animals 
or  materiel. 

Drivers  of  combat  vehicles  not  assigned  to  sections  arc 
likewise  responsible  to  the  supply  sergeant. 


120  MILITARY  SIGNAL  CORPS  MANUAL 

The  operators  are  responsible  for  the  serviceable  condition 
of  their  instruments  and  will  report  at  once  to  their  chiefs 
of  sections  any  need  of  repairs. 

The  linemen  are  responsible  for  maintaining  the  section 
lines  intact.  They  will  carry  the  necessary  equipment,  and 
will  report  to  the  chief  or  section  at  once  if  their  materiel 
is  not  in  their  possession  or  is  unserviceable. 

Messengers  are  responsible  for  the  delivery  of  all  mes- 
sages, no  matter  what  the  conditions. 

THE  SECTION 


103.  The  wire  section  is  normally  composed  of  13  mounted 
men  and  a  wire  cart  and  its  driver. 

The  organization,  in  detail,  is  as  follows: 

1  section  chief  (sergeant,  first  class). 

1  driver  (private,  first  class). 

3  station  squads,  each  consisting  of: 

1  lineman  "| 

1  messenger  |  assigned  by  section  chief  from  sergeant, 
1  horse  holder  }•  corporal,  private,  first  class,  or  private 
1  operator  according  to  qualifications. 

Total,  14.    J 


FORMATION 

104.  The  mounted  men  of  the  section  are  formed  in  column 
of  fours,  as  prescribed  in  The  Soldier  Mounted,  the  cart  horses 
2  yards  in  rear  of  the  mounted  men,  and  in  such  a  position  that 
the  pole  of  the  cart  is  in  prolongation  of  the  interval  between 
the  numbers  2  and  3  in  the  mounted  ranks. 


POSTS    AND    DUTIES    OF    INDIVIDUALS 

105.  The  chief  of  section  is  on  the  left  of  the  leading  four, 
two  or  file,  except  that  when  the  section  is  acting  alone  he 
may  go  where  his  services  are  most  needed. 

Each  four  constitutes  a  station  squad  and  includes  the  per- 
sonnel necessary  to  establish  and  operate  one  buzzer  station. 
Each  four  is  formed  from  right  to  left  as  follows:  No.  1,  the 
lineman;  No.  2,  the  messenger;  No.  3,  the  horse  holder;  No.  4, 
the  operator. 


THE  W IRE  COMPANY 


121 


^ — ^s—*,-  — 

*  ^ 

L        .       -1 


LEGEND 

I. LINEMAN. 

2. MESSENGER. 

0. HOUSEHOLDER. 

4. OPERATOR.' 

© OPERATOR,  If 

ON  CART 

MOUNT . 

DRAFT  HORSc. 

PACK  MULL  . 
D  5C.CTION  CHItr 
O  SOUMCK  MOUNTED. 


THE    WIRE    SECTION 

ABOVE — SECTION    IN    LINE 
TO   THE   RIGHT — SECTION    IN    COLUMK 


122  MILITARY  SIGNAL  CORPS  MANUAL 

Where  practicable,  noncommissioned  officers,  except  the  chief 
of  section,  should  be  assigned  to  duty  as  operators. 

DRILL  OF  THE   SECTION 
The  Guide 

106.  The  guide  of  the  section  is  the  chief  of  section.    In  the 
absence  of  the  chief  of  section  the  left  man  of  the  leading  rank 
is  the  guide. 

To  March  to  the  Front 

107.  1.   Forward,  2.   MARCH. 

Executed  as  prescribed  in  paragraph  81,  substituting  "sec- 
tion" for  "squad."  The  cart  maintains  its  position  2  yards  in 
rear  of  the  mounted  men. 

To  Halt 

108.  1.  Section,  2.  HALT. 

Executed  by   all  individuals   stopping  simultaneously. 

To  Change  Direction 

109.  1.  Column   right   (left),  2.   MARCH. 

The  section  remaining  in  column  of  fours,  the  fours  succes- 
sively execute  RIGHT  TURN  as  prescribed  in  paragraph  8S. 
The  cart  maintains  its  position  2  yards  in  rear  of  the  mounted 
men. 

To  March   to   the   Rear 

110.  Right   (left)  about,  2.  MARCH. 

The  section,  remaining  in  column  of  fours,  moves  to  the  right 
and  rear,  the  right  man  in  the  leading  rank  marching  over  half 
a  circle  whose  radius  is  2  yards.  The  cart  maintains  its  posi- 
tion 2  yards  in  rear  of  the  mounted  men. 

To    March    Obliquely 

111.  1.  Column   half  right   (left),  2.  MARCH. 

Executed  as  prescribed  for  changing  direction  except  that 
fours  successively  make  a  half  turn  to  the  right. 

To   make   a   slight   change   of   direction:    INCLINE  TO  THE 
RIGHT  (LEFT). 

Executed   as   in   paragrapli   82. 


THE  ]VIRE  COMPANY  123 

To  Form  the  Mounted  Men  of  the  Section  Into  Line 

112.  1.  Left   front   into   line,  2.  MARCH. 

The  chief  of  section  places  himself  on  the  right  of  the  lead- 
ing four. 

Executed  by  the  mounted  men  as  prescribed  in  paragraph 
295. 

The  cart  closes  up  to  2  yards  in  rear  of  the  right  four. 

This    movement    will    always    be    executed   to   the   left. 

Rule  1,  paragraph  133,  governs  the  gaits,  substituting  "four" 
for  "section." 

To  Re-fo.  m  the  Section  in  the  Normal  Formation 

113.  1.  Right  by  fours,  2.  MARCH. 

The  right  four  moves  straight  to  the  front ;  the  other  fours 
successively  oblique  to  the  right  front  when  disengaged  so  as 
to  follow  the  leading  four,  at  the  proper  distance. 

The  chief  of  section  takes  post  on  the  left  of  the  leading 
four. 

The  cart  follows  the  rear  four  at  2  yards  distance. 

Rule  2,  paragraph  133,  governs  the  gaits,  substituting  "four" 
for  "section." 

To  Form  the  Mounted  Men  in  Column  of  Twos  or  Files 

114.  1.  By    twos    (files),    2.    MARCH. 

Executed  by  the  mounted  men  as  indicated  in  paragraphs  92 
and  93. 

The  cart  follows  the  column  of  twos  or  files  at  2  yards  dis- 
tance. 

Rule  1,  paragraph  133,  governs  the  gaits,  substituting  "two" 
or  "file"  for  "section." 

To   Re-form    the    Mounted    Men    in    Column    of    Fours 

115.  1.  Form  fours,  2.  MARCH. 

Executed  by  the  mounted  men  as  indicated  in  paragraphs  94 
and  95. 

The  cart  follows  the  rear  four  at  2  yards  distance. 

Rule  1,  paragraph  133,  governs  the  gaits,  substituting  "two" 
or  "file"  for  "section." 

To  Open   Station 

116.  To  open    station   and   move   to  the    front   from   a   h?'t: 
OPEN  STATION.    At  this  command  the  linemen  of  the  first  and 
Second  fours,  the  messenger  of  the  first  four,  and  the  chief  of 
section  turn  out  of  the  column,  to  the  right,  the  horse  holder 


124  MILITARY  SIGNAL  CORPS  MANUAL 

and  operator  of  the  first  four  turn  out  of  the  column  to  the  left. 
The  two  linemen,  remaining  mounted,  prepare  to  follow  the 
reel  cart  and  lay  out  the  wire,  the  lineman  of  the  second  four 
starting  off  in  front. 

The  remaining  men  of  the  first  four  all  move  to  the  rear 
of  the  cart  and  dismount,  except  the  horse  holder,  to  whom  the 
horses  are  turned  over.  The  messenger  unties  the  wire  from 
the  cart  and  pulls  off  enough  slack  and  holds  it  or  makes  it 
fast  to  some  convenient  anchor.  The  operator  prepares  his 
buzzer,  connectors,  and  ground  rod,  and  opens  the  station  in 
the  location  indicated. 

When  it  becomes  necessary  for  the  lineman  of  the  second 
four  to  stop  for  the  purpose  of  making  a  tie,  or  for  other  rea- 
sons, he  is  passed  or  "leap  frogged"  by  the  lineman  of  the 
first  four.  This  practice  obtains  whenever  two  linemen  are 
working  together,  linemen  using  the  "leap  frog"  method  to 
the  best  advantage. 

Laying  the  Wire. 

117.  When  the  end  of  the  wire  has  been  removed  from  the 
cart  the  chief  of  section,  or,  in  his  absence,  the  senior  present, 
at  a  signal  from  messenger,  commands  :  DRIVE  ON,  at  which 
command  the  cart,  preceded  by  the  men  of  the  second  and  third 
fours,  except  the  lineman  of  the  second  four,  moves  out  over  the 
indicated  route,  at  first  slowly,  in  order  not  to  break  the  wire. 
The  two  linemen  follow  the  cart  attending  the  wire  until  the 
second  station   is  opened,  when  the  lineman   of  the  first   four 
returns  back  over  the  line  to  his   station.     His  place  is   taken 
on  the  line  work  by  the  lineman   of  the  second  four,  who.  is 
replaced  by  the  lineman  of  the  third  four. 

The  manipulation  of  the  machinery  of  the  wire  cart  for 
handling  the  wire  will  be  a  part  of  the  duty  of  the  cart  driver, 
unless  an  operator  be  placed  on  the  cart,  in  which  case  the 
latter  may  handle  the  clutch.  The  reel  must  always  be  stopped 
before  a  march  to  the  rear  is  taken  up. 

118.  The  chief  of   section   rides   near  the  cart,  or  wherever 
necessary  in  order  to  properly  supervise  the  laying  of  the  line. 
He  will  also  designate  a  scout  to  precede  the  section  from  100 
to  200  yards  and  select  a  route  in  the  immediate  front  for  the 
cart  to  follow.     The  driver  will  conform  to  the  signals  of  the 
scout.    If  the  section  is  in  march,  it  is  halted  before  giving  the 
command  for  opening  station.     As  each  station   is  established 
the  operator  will  call  up  the  initial  station. 

To  Close  Station 

119.  1.  CLOSE  STATION.    At  this  command  the  lineman  of 
the  distant  station  immediately  starts  back  over  the  line,  lay- 


THE  IV IRE  COMI'.lXy  125 

ing  out  the  wire  in  a  convenient  place  for  recovery.  The  oper- 
ator of  the  distant  station  calls  up  all  stations  on  his  line, 
send  G.  B.,  and  signs  his  station  call,  cuts  out  his  buzzer,  and 
mounts.  The  horse  holder  now  mounts  and  prepares  to  attend 
the  loop,  using  the  spare  pike  which  is  lashed  to  the  pole  of  the 
wire  cart.  The  messenger  takes  the  hand  guard  from  the  cart 
and  feeds  the  wire  upon  the  reel. 

Recovering    the    Wire 

120.  1.  REEL  UP. 

At  this  command  the  wire  cart  moves  off  back  over  the  line, 
reeling  up  the  wire.  As  the  loop  approaches  the  cart  the  man 
attending  it  will  call  out  clutch,  when  the  driver  will  throw  out 
the  clutch  in  order  to  allow  the  loop  to  drop  back. 

121.  Intermediate  stations  are  closed  by  the  command  close 
station,  and  when  the  cart  approaches  the  members  of  these 
stations  take  charge  of  the  work  of  recovering  the  line  back  to 
the  next  station. 

Members  of  the  section  not  engaged  in  laying  out  or  recov- 
ering the  line  ride  in  front  of  the  cart.  This  rule  is  general. 

As  the  cart  approaches  the  end  of  the  line  an  increased  gait 
will  be  taken  to  gain  sufficient  momentum  to  reel  up  the  slack. 
When  all  the  wire  is  on  the  reel  the  section  is  re-formed  in 
its  proper  place. 

THE  WIRE  PLATOON 

COMPOSITION    X 

122.  The  wire  platoon  is  composed  of  two  wire  sections  and 
is  commanded  by  a  lieutenant. 

FORMATION* 

123.  The  habitual  formations  of  the  platoon  are  the  order 
in  section  column  and  the  order  in  line. 

The  order  in  section  column  is  that  in  which  the  sections  of 
the  platoon  follow  each  other  in  the  order,  or  the  reverse  order, 
of  their  numbers  from  front  to  rear.  The  distance  between 
sections  is  2  yards. 

The  order  in  line  is  that  in  which  the  sections  of  the  platoon 
are  formed  abreast  of  each  other  in  the  order,  or  the  reverse 
order,  of  their  numbers  from  right  to  left.  The  interval  between 
the  sections  is  that  which  would  result  from  the  sections  mov- 
ing from  the  order  in  section  column  by  the  flank.  This  inter- 
val is  approximately  16  yards. 


126  MILITARY  SIGNAL  CORPS  MANUAL 

POSTS    AND    DUTIES    OF   INDIVIDUALS 

124.  In  the  order  in  section  column  the  post  of  the  lieutenant 
is  4  yards  opposite  the  center  of  the  platoon,  on  the  left  when 
the   first   section   of  the  platoon   is   leading  and   on   the   right 
when  the  column  is  reversed.     In  the  order  in  line  his  post  is 
midway  between  the  two  sections  and  in  line  with  the  leading 
fours   of  the  platoon.     When  acting  as   an   instructor  he  goes 
where  his  presence  is  necessary. 

The  lieutenant  commands  the  platoon.  The  posts  and  duties 
of  enlisted  men  in  the  platoon  are  prescribed  in  Section  II 
above. 

DRILL    OF    THE    PLATOON 

125.  The  platoon  is  drilled  in  accordance  with  the  principles 
and  by  the  methods  and  means  prescribed  for  the  section  and 
the  company. 

The  captain  may  assign  to  platoons,  for  purposes  of  drill 
and  instruction,  such  members  of  the  company  staff  as  he 
may  deem  advisable. 

THE  COMPANY 

FORMATION    OF    THE    COMPANY 

126.  The  habitual  formations  are :  The  order  in  section  col- 
umn, the  order  in  line,  and  the  order  in  platoon  column. 

127.  The  order  in  section  column  is  that  in  which  the  sections 
of  the  company  follow  each  other  in  the  order,  or  the  reverse 
order,  of  their  numbers,  from  front  to  rear.     The  distance  be- 
tween the  mounted  men  and  carts  in  a  section,  between  sections 
and  between  platoons  is  2  yards. 

The  order  in  line  is  that  in  which  the  sections  of  the  com- 
pany are  formed  abreast  of  each  other  in  the  order,  or  the 
reverse  order,  of  their  numbers  from  right  to  left.  The  interval 
between  the  sections  and  between  platoons  is  that  which  would 
result  from  the  sections  moving  from  the  order  in  section  col- 
umn by  the  flank. 

The  order  in  platoon  column  is  that  in  which  the  platoons  of 
the  company,  each  in  the  order  in  line,  follow  each  other  in  the 
order,  or  the  reverse  order,  of  their  numbers  from  front  to 
rear.  The  distance  between  the  platoons  is  that  which  would 
result  from  wheeling  the  platoons  from  the  order  in  line  to  the 
order  in  platoon  column. 


run.  in  RE  cos/r.ixy 


127 


? 


COMPANY    IN    COLUMN 


LEGEND 

4     CAPTAIN 

m     FIRST  LIEUTENANT 

U    M.S.E. 

&     FIRST  SERGEANT 

O    SECTION  CHIEF 

ffl     BUGLER 

£T  GUIDON 


i    CAPTAIN 

2vo*-*T"iT_~j 


tYOS. 


COMPANY    IN    LINK 


128  MILil  .IKY  SK.X.IL  COA'/'.V  MANUAL 

POSTS    OF   INDIVIDUALS 

128.  In  the  order  in  line  : 

Captain,  8  yards  in  front  of  the  center  of  the  company. 

Chiefs  of  platoons,  as  in  the  wire  platoon  in  the  order  in 
line. 

Master  signal  electrician,  4  yards  in  rear  of  the  center  of 
the  second  platoon.  The  master  signal  electrician  and  first 
sergeant  establish  the  line  of  file  closers. 

First  sergeants,  4  yards  in  rear  of  the  center  of  the  first 
platoon. 

Chiefs  of  sections,  as  prescribed  in  The  Section. 

Guidon,  abreast  of  the  front  rank  of  the  company  and  2 
yards  from  the  flank  toward  which  the  guide  has  been  an- 
nounced. 

Buglers,  in  line,  2  yards  in  rear  of  the  captain. 

Other  members  of  the  company  staff  when  present  mounted, 
posted  in  the  line  of  file  closers  in  order  of  rank  from  position 
of  the  first  sergeant  to  that  of  the  master  signal  electrician. 
They  conform  to  the  movements  of  the  above  noncommissioned 
officers. 

129.  In  order  in  section  column  : 

Captain,  opposite  the  center  of  the  column  and  16  yards  from 
the  flank ;  on  the  left  when  the  first  section  leads  and  on  the 
right  when  the  column  is  reversed. 

Chiefs  of  platoons,  4  yards  from  the  center  of  their  respec- 
tive platoons  and  on  the  same  side  as  the  captain. 

Master  signal  electrician,  4  yards  from  the  center  of  the 
second  platoon  and  on  the  flank  opposite  the  captain. 

First  sergeant,  4  yards  from  the  center  of  the  first  platoon 
and  on  the  flank  opposite  the  captain. 

Chiefs  of  sections,  as  prescribed  in  The  Section. 

Guidon,  abreast  of  and  2  yards  to  the  right  of  the  leading 
section 

•Buglers,  as  in  the  order  in  line. 

130.  In  the  order  in  platoon  column: 

Captain,  except  at  ceremonies,  16  yards  from  the  center  of 
the  company  and  on  the  side  of  the  guide.  At  ceremonies  as 
in  the  order  in  line. 

Chief  of  platoons,  master  signal  electrician,  first  sergeant, 
chiefs  of  sections,  guidon  and  buglers,  as  in  the  order  in  line. 

DRILL  OF  THE  COMPANY 

The  Guide 

131.  Chiefs   of   sections    supervise   tht   gait    and   direction   of 


THE  WIRE  COMPANY  129 

march  of  their  sections.  In  section  column,  the  guide  of  the 
leading  section  is  the  guide  of  the  company. 

The  guide  of  the  company  or  platoon  in  line  is  the  guide  of 
the  right  or  left  section. 

During  an  oblique  march  the  guide  of  the  company  is,  with- 
out indication,  the  guide  of  the  leading  section  on  the  side 
to  which  the  oblique  is  made. 

The  guidon  always  posts  himself  as  prescribed  in  paragraphs 
128-130.  Should  the  guide  be  changed,  he  hastens  to  his  new 
post,  except  that  he  does  not  change  post  during  an  oblique 
movement.  With  this  exception,  the  guide  is  always  toward 
the  guidon. 

Gaits 

132.  In  changes  of  formation,  the  section  which  establishes 
the  new  direction  and  rate  of  march  will  be  termed  the  direct- 
ing section. 

133.  The    following    rules   govern    the   gaits    during   changes 
of  formation : 

RULE  No.  1. — When  a  change  of  formation  requires  certain 
sections  to  gain  ground  so  as  to  reach  specified  positions  abreast 
of  the  directing  section,  an  increased  gait  may  or  may  not  be 
announced  for  the  movement.  If  an  increased  gait  is  an- 
nounced, the  directing  section  maintains  its  gait;  the  other 
sections  move  at  the  gait  announced  until  they  have  reached 
their  new  position,  when  they  take  the  gait  of  the  directing 
section. 

If  an  increased  gait  is  not  announced,  the  directing  section 
reduces  its  gait  one  degree;  the  others  maintain  their  gait  until 
they  reach  their  new  positions,  when  they  take  the  gait  of  the 
directing  section.  If  the  movement  is  executed  from  a  halt  or 
while  marching  at  a  walk,  and  an  increase  of  gait  is  not  or- 
dered, the  directing  section  advances  toward  the  front  of  the 
new  formation  and  halts  at  command. 

RULE  No.  2. — When  a  change  of  formation  requires  the  di- 
recting section  to  gain  ground  in  order  to  precede  the  other 
sections,  an  increased  gait  may  or  may  not  be  announced  for 
the  movement.  If  an  increased  gait  is  announced,  the  directing 
section  takes  the  increased  gait  at  once,  the  other  sections 
take  it  up  so  as  to  follow  the  movement  in  their  proper  order. 

If  an  increased  gait  is  not  announced,  the  directing  section 
maintains  its  gait,  the  others  reduce  the  gait  one  degree,  and 
take  the  gait  of  the  directing  section  in  time  to  follow  the 
movement  in  their  proper  order.  If  the  movement  is  executed 
from  a  halt  or  while  marching  at  a  walk  and  an  increase  of 
gait  is  not  ordered,  the  directing  section  moves  at  a  walk,  the 


130  MILITARY  SIGX.IL  COKPS  M.L\L\IL 

others  remain  halted  or  halt  and  take  up  the  gait  of  the  direct- 
ing section  as  before  explained. 

Reducing  gait  one  degree  is  to  be  understood  as  passing 
from  the  gallop  to  the  trot,  from  the  trot  to  the  walk,  or  from 
the  walk  to  the  halt.  Increasing  the  gait  one  degree  is  the  re- 
verse. 


To  Form  the  Company  Mounted 

134.  The  company  is  formed  dismounted  and  marched  to  the 
stables  by  the  first  sergeant  where  he  commands  BY  SECTION 
FALL  OUT.  The  drivers  then  harness  their  teams  and  the  men 
saddle  their  horses,  under  the  direction  of  the  chief  of  section. 
The  latter  then  causes  the  wire  cart  of  his  section  to  be  hitched 
up,  verifies  and  makes  an  inspection  of  his  section,  causes  it  to 
mount,  and  reports  the  result  to  his  chief  of  platoon.  The  chiefs 
of  platoons  then  make  an  inspection  of  their  platoons,  after 
which  the  company  is  formed  under  the  direction  of  the  senior 
chief  of  platoon  and  brought  to  rest.  On  the  arrival  of  the 
company  commander  the  company  is  brought  to  attention  by 
the  senior  chief  of  platoon.  The  captain  then  commands 
REPORT.  The  chiefs  of  platoons  then  report  in  the  order  of 
rank,  (SUCH)  PLATOON  IN  ORDER,  SIR,  or  reports  the 
deficiencies  shown  by  the  verifications  and  inspections.  The 
first  sergeant  then  reports  to  the  captain  as  prescribed  in 
regulations  governing  the  company  dismounted. 

The  master  signal  electricians,  other  members  of  the  com- 
pany staff,  if  present,  and  the  guidon,  take  their  posts  when 
the  company  is  formed.  The  buglers  report  to  the  captain  at 
such  time  and  place  as  he  may  direct.  The  chiefs  of  platoons 
join  their  platoons  at  the  stable  or  picket  line  and  superintend 
the  formation  of  their  platoons. 


To  Dismiss   the   Company 

135.  The  captain  commands  :  Dismiss  the  company. 

The  chief  of  platoons  and  the  master  signal  electrician  fall 
out.  The  company  is  returned  to  the  stables  or  picket  line  by 
the  first  sergeant,  who  then  commands  :  By  section,  FALL  OUT. 
The  chiefs  of  sections  supervise  the  placing  of  the  transpor- 
tation under  shelter  or  in  park;  the  horses  in  the  stable  or 
on  the  picket  line;  and  see  that  horse  equipment  and  harness 
has  been  properly  put  away,  and  that  all  equipment  has  been 
properly  disposed. 


THE  WIRE  COMPANY  131 

To  Align  the  Company 

136.  The  company  being  at  a  halt. 

If  the  section  on  the  side  toward  which  the  alignment  is  to 
be  made  is  not  in  proper  position,  the  captain  establishes  it 
in  the  position  desired,  and  commands :  1.  Right  (left),  2. 
DRESS,  3.  FRONT.  At  the  command  dress  the  other  sections 
move  forward  or  backward,  the  chiefs  of  sections  aligning 
themselves;  the  men  and  drivers  turn  their  heads  to  the  right 
and  dress  on  their  corresponding  elements  in  the  section  on 
their  right.  The  captain  places  himself  on  the  right  of  the 
leading  element  of  the  right  section,  facing  to  the  left.  He 
quickly  establishes  the  leading  element  of  the  next  section  to 
arrive  on  the  line,  and  superintends  the  alignment  of  the  other 
sections  as  they  arrive  on  the  line.  The  captain  then  com- 
mands FRONT,  and  takes  his  post. 

To  March  to  the  Front 

137.  1.  Forward,  2.  MARCH. 

Executed  simultaneously  by  all  the  sections  moving  straight 
to  the  front,  taking  care  to  maintain  their  proper  relative  posi- 
tions in  the  formation. 

To  Halt 

138.  1.  Company,  2.  HALT. 

Executed  by  all  sections  stopping  simultaneously,  but  not 
suddenly. 

To  March  by  the  Flank 

139.  1.  By  the  right  (left)  flank,  2.  MARCH. 

Executed  simultaneously  by  all  the  sections  executing  column 
right,  as  prescribed  in  paragraph  109. 

140.  If   the   company    is   in    line,   with    closed    intervals,   the 
following   modifications    apply:    The   movement    is    successive; 
the    section    on    the    indicated   flank   begins   the   movement   by 
executing  column   right ;   the  others   take   it   up   in   turn   so  as 
to  follow,  at  the  proper  distance,  in  the  track  of  the  sections 
which    preceded    them.      If    executed    while    marching,    all    the 
sections,  except  the  one  on  the  indicated  flank,  halt  and  then 
resume  the  march   so   as   to  follow   at   the   proper  distance  in 
the  column. 

To   March   to   the   Rear 

141.  1.  Right  (left)  about,  2.  MARCH. 


132  MILITARY  SIGNAL  CORPS  MAXUAL 

Executed  simultaneously  by  all  sections  as  prescribed  in 
paragraph  110,  taking  care  to  quickly  track  the  section  pre- 
ceding them  in  the  new  formation,  if  the  company  was  in  col- 
umn at  the  command,  or  to  promptly  take  up  the  announced 
guide  if  it  was  in  line. 

142.  If  the  company  is  in  line  with  closed  intervals,  the  fol- 
lowing  modifications    apply:    The    captain    first    commands:    1. 
Right  sections  forward,  2.  MARCH.     The  right  section  of  each 
platoon  moves  forward  so  as  to  clear  the  left  section.     If  the 
captain   orders   an   increased  gait  for  the  maneuver,  the  righi 
sections  take  the  gait  indicated ;  if  an  increased  gait  is  not  or- 
dered, the  left  sections  reduce  the  gait  one  degree,  or,  if  halted, 
they  remain  halted.    As  soon  as  the  right  sections  are  clear  of 
the  left  sections  the  captain  gives  the  command  for  the  about, 
which  is  executed  by  all  the  sections  at  the  gait  of  the  right 
sections.     On  the  completion  of  the  about  the  sections  in  rear 
increase  the  gait  so  as  to  move  up  to  their  positions  in  line. 

To   March   Obliquely 

143.  1.  Sections,  2  Column  half  right  (left),  3.  MARCH. 

All  the  sections  execute  column  half  right  simultaneously, 
as  prescribed  in  paragraph  111.  The  sections  move  on  parallel 
lines.  The  guide  of  each  section  takes  care  to  align  himself 
on  the  guide  of  the  section  toward  which  the  movement  is 
made.  To  resume  the  original  direction,  the  command  will  be : 
1.  Sections,  2.  Column  half  left  (right),  3.  MARCH. 

To  Change  Direction 

144.  Being    in    section    column:     1.    Column    right    (left),    2. 
MARCH. 

The  leading  section  executes  column  right,  as  explained  in 
paragraph  109;  the  sections  in  rear  follow  the  leading  section 
and  turn  on  the  same  ground. 

Column  half  right  (half  left)  is  similarly  executed,  except 
that  the  turn  is  only  45°. 

145.  Being  in   line  :  1.  Right  (left)  turn,  2.  MARCH,  3.  Com- 
pany,   4.    HALT.      The    pivot    section    executes    column    right. 
The   other    sections    increase    the   gait   one    degree,   preserving 
their  intervals  from  the  pivot  section  and  take  the  gait  of  the 
latter  on  arriving  abreast  of  it. 

Company  right  half  (left  half)  turn  is  similarly  executed,  ex- 
cept that  the  pivot  section  executes  column  half  right. 

If  the  company  is  marching  at  a  gallop,  the  pivot  section 
will  take  the  canter  at  the  command  march;  the  other  sections 
will  take  the  canter  when  abreast  of  the  directing  section. 
When  all  of  the  sections  are  in  line,  the  captain  commands : 
1.  Gallop,  2.  MARCH. 


THE  WIRE  COMPANY  133 

To  Close  or   Extend   Intervals   in  Line 

146.  1.    On    (such)    section,    2.    Close    (extend)    intervals,    3. 
MARCH. 

The  normal  closed  interval  is  8  yards.  If  the  captain  wishes 
any  other  interval  than  the  normal  closed  or  normal  interval 
to  be  taken,  he  announces  the  interval  before  giving  the  second 
command;  for  example:  1.  On  first  section,  2.  To  20  yards,  3. 
Extend  intervals,  4.  MARCH. 

The  indicated  section  moves  straight  to  the  front,  the  other 
sections  incline  toward  or  away  from  the  indicated  section  and 
move  to  the  front  when  at  the  proper  interval.  Paragraph 
133  governs  the  gait. 

To  Form  Section  Column  to  the  Front  from  Line 

147.  1.  Right  (left)  by  section,  2.  MARCH. 

The  right  section  moves  straight  to  the  front.  The  other 
sections,  in  turn,  move  by  the  right  flank,  and  follow  in  the 
column  at  2  yards  distance.  Rule  2,  paragraph  133  governs 
the  gait. 

To  Form  Line  to  the  Front  from  Section  Column 

148.  To  the  front :  1.  Right  (left)  front  into  line,  2.  MARCH. 

The  leading  section  moves  straight  to  the  front.  Each  sec- 
tion in  rear  executes  column  half  right  until  opposite  its  place 
in  line,  when  it  executes  column  half  left,  moves  to  the  front, 
and  takes  its  place  on  the  line.  Rule  No.  1,  paragraph  133, 
governs  the  gait. 

To  Form  Line  to  the  Right  (Left)  from  Section  Column 

149.  On    the    right     (left)  :    1.    On    right    (left)    into    line,    2. 
MARCH. 

The  leading  section  executes  column  right  and  moves 
straight  to  the  front  in  the  new  direction  ;  the  other  sections 
move  forward  beyond  the  preceding  sections,  and  successively 
execute  column  right  when  opposite  their  positions  in  line  with 
proper  intervals,  and  then  move  forward  until  abreast  of  the 
leading  section.  When  an  increased  gait  \s  ordered  all  of  the 
sections  will  take  it,  but  the  leading  section  will  resume  the 
original  gait  when  it  has  turned  out  of  column.  If  moving  at 
a  trot  or  gallop  and  no  increased  gait  is  ordered  the  leading 
section,  after  completing  the  turn,  will  decrease  its  gait  one 
degree.  As  here  modified,  Rule  No.  1,  paragraph  133,  for  gaits 
applies. 


134  MILITARY  S1GXAL  CORPS  UAXl'AL 

150.  To  form  on  right  (left)  into  line  at  closed  intervals  the 
captain  commands  :  At  closed  intervals  before  giving  the  pre- 
scribed commands  for  forming  line;  the  company  is  then  formed 
with  8  yards  instead  of  the  normal  intervals. 

151.  To  the  right  (left)  :  I.  Right  (left)  into  line,  2.  MARCH. 
The  leading  section  executes  column  right  and  moves  straight 

to  the  front  in  the  new  direction ;  the  other  sections  move 
forward  and  successively  executes  column  right  when  they 
are  in  rear  of  their  places  in  line  to  the  right  (left)  of  the 
leading  section  at  closed  intervals.  They  then  move  forward 
until  abreast  of  the  leading  section.  Rule  No.  1,  paragraph  133, 
governs  the  gaits. 

152.  To  form  line  at  intervals  other  than  normal  or  closed 
intervals  the  captain  commands  :    At  —  yards  interval,  before 
giving  the  prescribed  commands  for  forming  line;  the  company 
is  then  formed  with  the  indicated  intervals  between   sections. 

To  Form  the  Mounted  Men  of  the  Sections  in  Line 

153.  This  will  always  be  done  to  the  left. 

1.  Sections,  2.  Left  front  into  line,  3.  MARCH. 

This  will  be  executed  by  the  sections  as  prescribed  in  para- 
graph 112. 

To  Re-form  the  Sections  in  the  Normal  Formation 

154.  1.  Sections,  2.  Right  by  fours,  3.  MARCH. 

To  Form  Platoon  Column  to  the  Front  From  Section  Column 

155.  1.  Platoons,  2.   Right   (left)   front   into  line,  3.   MARCH. 

The  leading  section  of  each  platoon  moves  straight  to  the 
front.  The  rear  section  executes  column  half  right  and  then 
column  half  left,  when  by  so  doing  it  will  have  its  normal  in- 
terval from  the  leading  section. 

Rule  No.  1,  paragraph  133,  governs  the  gaits. 

To  Form  Platoon  Column  to  the  Flank  From  Section  Column 

156.  1.  Column  of  platoons,  first  platoon  by   the  right   (left) 
flank,  2.  MARCH. 

At  the  first  command  the  chief  of  the  leading  platoon  com- 
mands :  1.  By  the  right  flank.  At  the  command  MARCH  each 
section  in  the  leading  platoon  executes  column  right  as  before 
described. 

At  the  first  command  the  chief  of  the  rear  platoon  cautions 


THE  WIRE  COMPANY  135 

CONTINUE  THE  MARCH.  When  it  arrives  in  rear  of  the 
leading  plato»n,  the  chief  of  platoon  commands:  By  the  right 
(left)  flank,  adding  MARCH  in  time  to  follow  the  leading 
platoon  in  trace. 

To  Form  Section  Column  to  the  Front  From  Platoon  Column 

157.  1.  Right  (left)  by  section,  2.  MARCH. 

The  right  sections  of  the  platoons  move  straight  to  the  front. 
The  left  sections   execute   column  half  right   and  then  col- 
umn half  left,  and  follow  in  the  rear  of  the  leading  sections. 
Rule  No.  2  governs  the  gaits. 

Being  in  Line,  to  Form  Platoon  Column,  to  the  Right  (or  Left) 

158.  1.  Platoons,  2.  Right  (left)  turn,  3.  MARCH,  4.  Company, 
5.  HALT. 

The  right  section  of  each  platoon  executes  column  right. 
The  other  sections  increase  the  gait  one  degree,  preserving 
their  interval  from  the  right  section,  and  take  the  gait  of  the 
latter  on  arriving  abreast  of  it. 

Being  in   Platoon  Column,  to  Form  Line  to  the   Right   (Left) 

159.  1.    Platoons,    2.    Right    (left),    3.    MARCH,    4.    Company, 
5.  HALT. 

Executed  as  prescribed  in   the  preceding  paragraph. 

Route   Order   and   at    Ease 

160.  Marching  in  any  formation  :  1.  ROUTE  ORDER,  or  1. 
AT   EASE.     Executed   as   prescribed   in   the    Soldier   Mounted. 

The  section  column  is  the  habitual  column  of  route.  The 
mounted  men  of  the  sections  may,  when  conditions  require  it. 
be  formed  in  column  of  twos  instead  of  column  of  fours.  Be- 
ing in  march,  route  order  or  at  ease  are  executed  according  to 
the  principles  already  prescribed.  Sabers  are  returned  if 
drawn.  To  resume  attention  the  captain  commands  :  Company, 
ATTENTION. 

The  captain  marches  8  yards  in  front  of  the  leading  ele- 
ment, followed  at  2  yards  distance  by  the  trumpeters  and  guidon, 
the  latter  on  the  right;  the  chiefs  of  platoons  usually  march 
near  the  rear  of  their  platoons,  but  they  and  the  chiefs  of  sec- 
tions may  go  wherever  their  presence  is  necessary ;  the  file 
closers  march  where  the  captain  directs. 

To  avoid  dust,  the  captain  may  direct  the  officers  and  file 
closers  to  march  on  the  windward  side. 


136  MILITARY  SIGNAL  CORPS  MANUAL 

EMPLOYMENT  IN  THE  FIELD 


161.  The  main  equipment  of  each  of  the  four  wire  sections 
is  a  two-horse  reel  cart  carrying  5  miles  of  Signal  Corps  field 
wire  and  the  buzzers  and  other  apparatus  for  establishing  the 
necessary  stations.    Wire  can  be  laid  out  and  recovered  at  fast 
gaits  and  stations  established  or  discontinued  in  a  few  seconds. 

Buzzer  wire  carriers,  each  with  a  quarter  mile  of  buzzer 
wire,  can  be  used  in  emergency  or  where  it  is  impracticable 
to  lay  the  field  wire.  Each  section  carries  \l/2  miles  of  buzzer 
wire  and  4  buzzer  wire  carriers. 

162.  Whenever  practicable,  a   reserve  of  equipment   will  be 
kept  on  hand  to  provide  for  a  sudden  move  of  the  headquarters 
or   other    station.     For    this    reason    the    company   commander 
must  take  every  opportunity  to  reel  up  wire  no  longer  used. 
This    can    often    be    done    as    the    action    progresses  or  after  a 
move  of  headquarters. 

163.  When  a  wire  line  is  discontinued,  every  effort  will  be 
made  to  recover  the  wire,  and    wire    or    materiel    will    not    be 
abandoned  unless  its  recovery  has  become  impracticable. 

164.  When  lines  are  laid  within  the  zone  of  fire  or  observa- 
tion of  the  enemy,  the  men  laying  the  lines  will  take  advantage 
of  cover  to   conceal  their  position   and   movements.     Sections 
should    not    be    placed    in    positions    exposed    to    the    enemy,    nor. 
on  the  other  hand,  in  places  where  it  will  be  difficult  for  those 
for  whose  use  the  line  is  established  to  find  them  readily. 


ON    THE    MARCH 

165.  The  position  of  the  wire  company  in  the  column  is  not 
important    unless    resistance   is    expected.     In    the    latter   case, 
the  company  should  be  where  sections  and  platoons  may  pro- 
ceed promptly  from  division  headquarters  and  lay  lines  to  the 
brigades  and  other  units  as  soon  as  they  deploy.     To  be  in  a 
position  to  meet  this  requirement,  the  company  should  be  at 
or  near  the  head  of  the  main  body. 

166.  In  case  it  is  desired  for    tactical    reasons    to    maintain 
communication    between    different    parts    of   a   division    on    the 
march,  this  service  should  be  rendered  by  means  of  the  radio 
sets  rather  than  by  the  use  of  wire  lines.    The  use  of  the  latter 
on  the  march  is  more  exhausting  to  the  Signal  Corps  personnel 
and  uses  wire  which  may  be  urgently  needed  for  combat  line? 
at  any  moment  \\hen  contact  with  the  enemy  is  possible. 


THE  WIRE  COMPANY  137 


IN   BATTLE 

167.  When  resistance  is  encountered  and  the  division  is  de- 
ploying opportunity  for  the  most  useful  and  important  applica- 
tion   of    the    wire    company    is    presented.     The    division    com- 
mander or  a  representative  will  indicate  by  formal  field  order 
or  otherwise  the  wire  lines  it  is  desired  to  establish.    As  soon 
as  possible,  the  captain  designates  an  initial  point  for  the  be- 
ginning of  wire   laying  and  assigns   sections   and   platoons   to 
suitable  tasks. 

168.  The  strictest  economy  of  wire  and  other  materiel  should 
be  observed  in  planning  for  and  laying  the  lines  to  the  end  that 
same  be  not  uselessly  expended  and  found  exhausted  at  a  critical 
stage.     As  large  a  reserve  as  possible  of  wire  and  equipment 
should  be   assembled  at  a   central  point  with   which   to  effect 
replacements  and  meet  unexpected  demands.     It  is  advantage- 
ous and  most  usual   to  play  wire  from  a   point   near  division 
headquarters  outward.     A  principal  advantage  lies  in  the  fact 
that  the  reel  cart  is  thus  placed  at  the  end  where  changes  of 
position  are  most  frequent. 

IN  CAMP 

169.  When  the  division  goes  into  bivouac  or  camp  the  wire 
company  establishes  such  tactical  lines  of  information  as  may 
be  indicated.     These  will  usually  be  wire  lines  on  the  ground 
and  will  connect  division  headquarters  with  brigades  and  im- 
portant outposts  and  observation  points. 

RESERVE   WIRE  CARTS 

170.  The  two  extra  wire  carts  in  the  company  carry  10  miles 
of  field  wire  each,  which  constitutes  a  reserve  supply  for  issue 
to   subordinate   units   when   necessary.     The   captain   regulates 
the  issue  and  use  of  this  reserve  materiel  in  the  most  judicious 
manner  for  supplementing  and  replacing  the  equipment  pertain- 
ing to  subordinate  units.    The  reserve  wire  carts  and  the  com- 
pany instrument  wagon  constitute  a  part  of  the  company  com- 
bat train  and  should  march  in  rear  of  the  company. 

RECONNAISSANCE 

171.  A  most  important  preparatory  measure  for  units   of  a 
wire  company  to  take  before  actually  laying  indicated  ground 
lines  of  information  is  to  provide  for  as  complete  a  reconnais- 
sance as  time  will  permit  of  the  route  to  be  followed  in  laying 


138  MILITARY  SIGNAL  CORPS  MANUAL 

the  wire.  Such  reconnaissance  will  be  accomplished  by  suitable 
reconnoitering  or  scouting  parties  detailed  from  the  personnel 
of  the  sections  or  by  such  detachments  from  the  company  staff 
as  the  captain  may  direct. 

172.  These  scouting  parties  will  examine  carefully  the  gen- 
eral route  to  be   followed  in   laying  the   wire  with   a  view  to 
selecting  the  particular  route  (a)  which  best  utilizes  the  exist- 
ing materiel  and  artificial   cover   along   the   route ;    (b)    which 
offers  the  least  difficult  terrain  to  traverse;  and  (c)  due  regard 
being  had  for  the  above,  that  route  which  is  the  shortest  and 
which    involves    the    laying    of    the    least    possible    amount    of 
wire. 

173.  It  is  incumbent  on  the  scouting  party  in  front  to  mark 
the  route  so  that  uncertainty  may  not  arise  as  to  the  direction 
to  be  followed.    A  marker  is  made  to  understand  clearly: 

(a)  The  route  to  be  followed. 

(b)  The  particular  unit  or  units  to  be  guided. 

(c)  The  message,  if  any,  to  be  delivered. 

(d)  Other  directions  to  be  carried  out  or  the  route  he  is  to 
follow  in  order  to  rejoin  his  party. 

174.  The  marker  indicates  the  correct  route,  acting  as  guide 
if  necessary  over  terrain  where  the  route  is  difficult  to  follow, 
and  as  soon  as  his  mission  is   fulfilled  hastens  to  replace  the 
next  marker  or  to  rejoin  his  detachment  or  detail. 

By  the  establishment  of  well-understood  conventions,  or  by 
the  use  of  suitable  signs,  the  number  of  markers  may  be  re- 
duced. Thus,  it  should  be  understood  that  a  main  traveled 
road  is  not,  without  indication,  to  be  left  for  one  that  is  notice- 
ably less  traveled,  and  that  a  straight  road  is  not,  without  indi- 
cation, to  be  left  for  one  which  deviates  from  it.  By  marking 
arrows  on  trees  and  buildings,  or  by  other  suitable  signs,  un- 
certainties of  a  minor  nature  may  be  removed.  In  important 
cases,  however,  a  marker  should  always  be  left  at  places  where 
a  reasonable  doubt  may  arise. 

When  the  head  of  the  column  for  which  the  route  is  being 
marked  comes  within  view  of  a  marker  the  latter  signals  the 
former,  and  the  former  acknowledges  with  a  countersignal. 
Both  signal  and  countersignal  should  be  distinctive  and  should 
have  been  previously  agreed  upon.  The  same  signal  and 
countersignal  are  used  throughout  the  detail. 

175.  The  men  designated  for  the  foregoing  are  selected  for 
special  aptitude   from   the  personnel   of  the   sections   and   the 
company  staff  and  are  carefully  instructed  in  the  duties  they 
are  to  perform. 

It  will  be  found  advantageous  to  have  those  men  of  a  section 
designated  for  scout  duty  grouped  in  the  station  squad  which  is 
last  to  establish  its  station. 


THE  WIRE  COMPANY  139 

Additional  men  are  designated  from  time  to  time  to  receive 
the  instruction  so  that  substitutes  may  be  available.  Alert, 
cool-headed,  and  intelligent  men  should  be  selected  for  this 
duty;  they  should  be  good  horsemen  and  have  good  eyesight 
and  hearing. 

Each  scout  should  be  provided  with  a  good  field  glass,  a 
compass,  a  watch,  a  whistle,  a  field  message  book,  and  a  pencil. 

176.  The  training  of  a  scout  should  have  for  its  object: 

1.  To  develop  his  powers  _of  observation. 

2.  To  teach  him  what  to  look  for  and  how  to  recognize  it. 

3.  To  teach  him  how  to   report   intelligently  and  concisely. 

The  scout's  powers  of  observation  and  description  are  devel- 
oped first  of  all  by  simple  exercises.  Thus  he  may  be  required 
to  look  at  a  given  section  of  terrain  and  describe  what  he  sees 
in  it. 

The  scout  is  made  to  appreciate  the  lay  of  the  land  as  indi- 
cated primarily  by  its  drainage,  and  secondarily  by  other  nat- 
ural features,  and  by  the  works  of  man.  A  good  eye  for  coun- 
try is  thus  to  be  acquired;  the  scout  learns  to  appreciate  the 
configuration  of  a  terrain  which  may  be  only  partially  visible 
to  him,  and  thus  to  deduce  the  most  favorable  routes  for  trav- 
ersing it  and  the  most  probable  positions  for  hostile  occupation. 

The  scout  must  also  be  taught  to  distinguish  troops  of  the 
different  arms,  to  recognize  their  formations,  and  to  familiarize 
himself  with  their  usual  methods  of  action. 

The  scout  must  be  trained  (a)  to  use  field  glasses;  (b)  to 
read  maps ;  (c)  to  make  reports,  both  verbal  and  written ;  (d) 
to  make  routs  sketches. 


THE   RADIO  COMPANY 

GENERAL 
-FUNCTION  AND  EMPLOYMENT 

177.  The  radio  company  is  used  by  the  commander  of  a  divi- 
sion   for    maintaining    communication    with    adjacent    columns, 
with  the  divisional   cavalry,  and  in  other  instances  when  dis- 
tance, the  character  of  service,  and  the  nature  of  the  terrain 
prevent  the  laying  of  wire  lines.     The  radio  company  usually 
serves    to    connect    division    headquarters    with    the    divisional 
trains  and,  pending  the  construction   of  semi-permanent   lines, 
with    the    radio   station    at   Army    corps   headquarters    in    rear. 
These  radio  facilities  may  also  be  used  to  intercept  messages 
sent  by  the  enemy  or  to  interfere  with  the   operation   of  his 
radio  stations. 

ORGANIZATION 

178.  The  radio  company  is  organized  into  the  necessary  head- 
quarters and  company  staff,  two  platoons   of  two  pack  radio 
sections  each,  and  one  wagon  radio  section. 

For  drill  the  company  is  formed,  as  above,  the  wagon  radio 
section  forming  a  provisional  platoon  on  the  left  of  the  company. 
In  the  field  or  on  the  march  the  company  instrument  wagon 
forms  a  fourth  platoon  under  command  of  the  supply  sergeant. 

179.  The   organization,   in    detail,   is    as   follows: 

1  captain.  1  farrier    (corporal). 

2  first  lieutenants.  1   saddler  (corporal). 

1  master  signal  electrician.  1  mechanic   (corporal). 

1  first   sergeant   (sergeant,  first  2  cooks. 

class).  1  driver   (private,  first   class). 

1  supply  sergeant  (sergeant)  2  buglers  (private,  first  class, 

1  stable    sergeant    (sergeant).  one    acting  as   guidon). 

1  mess  sergeant  (sergeant).  4  radio    sections,   pack. 

1  horseshoer.  1  radio  section,  wheel. 
1  clerk   (corporal). 

140 


THE  RADIO  COMPANY 


141 


i«(  rr  — 


t     i 


PACK    SECTION    IN     LINE 


2S\  rt 

r*  "-"«  FT  ft  rL^-«  rr-J.«  ri  *.t 

^zH^mmmi 


LEGEND 
MOUNT. 
OKAr~  house. 

^      PACK  MULc.  . 
D      SECTION  CMKF  . 
O      SOLDIER  MOUNTED . 


PACK  SECTION 


RADIO  SECTION. 


142  MILITARY  SIGNAL  CORPS  MANUAL 

DUTIES    OF    INDIVIDUALS 

180.  The    duties    of    individuals    in    the    various    grades    are 
identical  with  those  of  the  same  grades  in  the  wire  company. 

THE  PACK  RADIO  SECTION 
COMPOSITION 

181.  The    pack   radio    section    is    normally   composed   of    10 
mounted   men   and  3  pack   mules,   designated   the   "generator" 
mule,  the  "chest"  mule,  and  the  "kit"  mule.     If  a  fourth  pack 
mule   be   present   with    the    section   it   will   be   designated   the 
"supply"  mule. 

The   organization,  in   detail,  is   as   follows: 

1  section  chief  (sergeant,  first  class). 

2  operators    (1    sergeant,    1    corporal). 

1  messenger  (private,  first  class). 

4  antenna  and  counterpoise  men   (1   corporal,  3  privates, 
first  class). 

2  horseholders   (1   private,  first  class,  1   private). 

Total,  10. 

FORMATION 

182.  The  section  is  formed  in  column  of  twos  as  prescribed 
in   "The   Soldier   Mounted."     Each   mule   is   led  by  one  of  the 
men  and,  with  its  driver,  forms   a  two. 

POSTS    AND    DUTIES    OF    INDIVIDUALS 

183.  The  chief  of  section  is  on  the  left  of  the  leading  two 
except  that  when  the  section  is  acting  alone  he  may  go  where 
his  services  are  most  needed. 

The  other  men  are  numbered  from  1  to  9,  Nos.  1  and  2,  the 
operators,  form  the  leading  two,  No.  1,  the  sergeant  operator, 
on  the  right.  These  are  followed  by  Nos.  3  and  4,  horseholders, 
and  No.  5,  the  messenger,  leading,  respectively,  the  kit,  gen- 
erator, and  chest  mules.  Mule  drivers  march  on  the  left  of 
their  led  mules.  The  mules  are  followed  by  Nos.  6,  7,  8,  and  9, 
antenna  and  counterpoise  men,  in  column  of  twos  with  Nos.  6 
and  8  on  the  right.  It  is  the  duty  of  No.  6  to  observe  the  packs 
and  keep  up  any  lagging  mules.  The  antenna  squad  corporal 
is  No.  9.  If  a  supply  mule  be  present  it  is  led  by  No.  6,  and 
the  duty  of  observing  packs  and  keeping  up  lagging  mules  de- 
volves upon  No.  8, 


THE  RADIO  COMPANY  143 

It  is  the  duty  of  all  men  so  far  as  they  may  be  able  in 
addition  to  leading  their  own  mules,  to  urge  forward  the  mule 
immediately  in  front. 

DRILL  OF  THE  SECTION 


The   Guide 

184.  The  guide  of  the  section  is  the  chief  of  section.  In  the 
absence  of  the  chief  of  section,  the  left  man  of  the  leading  rank 
is  the  guide. 


The  Marchings 

185.  The  pack  section  executes  the  march  to  the  front,  the 
halt,  the  changes  of  direction,  the  march  to  the  rear,  and  the 
oblique  march,  as  prescribed  for  the  wire  section,  substituting 
"twos"  for  "fours"  wherever  found  and  omitting  reference  to 
the  carts. 

To  Form  to  the  Front  in  Two   Lines 

186.  1.  Left  front  into  line,  2.  MARCH. 

This  will  be  executed  by  forming  in  two  lines,  with  2  yards 
distance,  the  first  line  being  composed  of  the  men  not  leading 
mules,  the  second  being  composed  of  the  pack  mules  and  their 
drivers.  Each  line  is  formed  in  a  manner  similar  to  that  de- 
scribed in  paragraph  91.  Mule  drivers  wait  until  the  mounted 
men  in  rear  pass  them  before  forming  front  into.  line.  The 
chief  of  section  takes  his  place  on  the  right  of  the  leading 
rank. 

This  movement  will  always  be  executed  to  the  left. 

Rule  1,  paragraph  133,  governs  the  gaits,  substituting  "'two" 
for  "section." 

To    Re-form    the    Section    in    Normal    Formation 

187.  1.  Right  by  two.,  2.  MARCH. 

The  right  two  moves  straight  to  the  front,  the  other  twos 
successively  oblique  to  the  right  front,  when  disengaged,  so  as 
to  follow  in  their  proper  places  in  column.  The  chief  of  sec- 
tion resumes  his  post  on  the  left  of  the  leading  two. 

Rule  2,  paragraph  133,  governs  the  gaits,  substituting  "two" 
for  "section." 


144  MILITARY  S1CXAL  CORPS  MANUAL 

To   Form   in    Column    of  Files 

188.  1.  By  file,  2.  MARCH. 

Executed  as  indicated  in  paragraph  93.  Each  mule  driver 
precedes  his  mule. 

Rule  2,  paragraph  133,  governs  the  gaits,  substituting  "two" 
for  "section." 

To  Re-form  in  Column  of  Twos 

189.  1.  Form  twos,  2.  MARCH. 

Executed  according  to  the  principles  indicated  in  paragraph 
95. 

Rule  1,  paragraph  133,  governs  the  gaits,  substituting  "file" 
for  "section." 

To  Open  Station 

190.  Being    in    normal    formation :    1.  Open  station,   2.  DIS- 
MOUNT. 

At  the  command  OPEN  STATION,  Nos.  3  and  4  stand  fast; 
No.  1  executes  individual  right  about,  chief  of  section  and  No.  2 
left  about ;  No.  6,  moving  along  right  flank  of  column,  comes  In 
alongside  No.  1  ;  No.  8  comes  in  alongside  No.  6;  No.  7,  moving 
along  left  flank  of  column,  comes  in  alongside  the  chief  of  sec- 
tion;  No.  9  comes  in  alongside  No.  7;  No.  5  leads  his  mule  left 
front  into  line  on  No.  4.  At  the  command  DISMOUNT,  all  pass 
reins  over  horses'  heads  and  dismount.  Chief  of  section,  Nos,  1, 
2,  6,  7,  8,  and  9  turn  their  horses  over  to  No.  3,  and  proceed  to 
unpack  the  generator  and  chest  mules.  Nos.  4  and  5,  holding 
their  mules  in  place,  move  their  horses  out  of  the  way.  No.  1 
working  on  right  side  and  No.  2  on  left  side,  with  No.  8  assist- 
ing, unpack  generator  mule.  No.  6  working  on  right  side  and 
No.  7  on  left  side,  No.  9  assisting,  unpack  chest  mule.  The 
equipment  will  be  placed  on  ground  1  yard  in  rear  of  mules, 
iron  ferrules  of  mast  pointing  to  rear.  Nos.  4  and  5,  after  see- 
ing that  all  loose  straps  and  cinchas  are  crossed  over  mules, 
lead  off  their  horses  and  mules  and  turn  them  over  to  No.  3. 
No.  4  moves  up  on  the  right  and  No.  5  on  the  left  of  No.  3.  As 
soon  as  the  mules  are  unpacked  Nos.  6  and  7  open  antenna  bag 
and  distribute  antenna  reels,  the  chief  of  section  places  top 
insulator  into  top  joints  of  mast,  and  distributes  pins  to  Nos.  1, 
2,  6,  and  7,  who  secure  antenna,  snap  their  antenna  into  in- 
sulator, and  reel  out  their  antenna  wires.  No.  1  goes  to  right 
and  No.  2  to  left  of  horses,  their  antenna  wires  forming  an 
angle  cf  90  degrees,  No.  6  opposite  No.  2  and  No.  7  opposite 
No.  1,  and  then  face  mast  and  watch  the  chief  of  section  for 


THE  RADIO  COMPANY  145 

signals.  The  chief  of  section  and  No.  4  then  raise  the  mast  hand 
over  hand;  No.  5,  assisted  later  by  No.  4,  connects  up  chest  and 
generator,  antenna,  and  counterpoise  leads.  As  soon  as  bottom 
joint  is  in  place  and  mast  vertical,  chief  commands  tie  in, 
when  the  antenna  men  secure  their  antenna  cords  to  pins  and 
return  to  mast ;  Nos.  8  and  9  reel  out  the  counterpoise  directly 
under  the  antenna  wires.  In  their  absence  this  will  be  done 
by  Nos.  6  and  7.  The  chief  of  section  details  the  necessary 
operators,  messengers,  men  to  turn  generator,  guards  to  pro- 
tect antenna  and  over  animals. 

Each  man,  having  a  permanent  assignment  of  duty,  soon 
learns  to  do  his  part  quickly,  and  after  the  men  have  become 
proficient  in  handling  the  equipment  the  entire  operation  of 
unpacking  and  opening  station  may  be  effected  by  the  com- 
mand open  station. 

To  Close  Station 

191.  At  the  command  CLOSE  STATION,  the  chief  of  section 
and  No.  4  immediately  start   lowering  the  mast;  Nos.   1,  2,  6, 
and  7  move  rapidly  to  their  respective  antenna  cords,  face  the 
mast,  and   watch   for   signals.     They  place   their   antenna   pins 
in  leggings  and,  when  the  mast  is  down,  reel  up  without  wait- 
ing for  command.     The   chief   of   section   unsnaps   all  antenna 
wires  from  top  insulator,  throws  them  clear,  and  then  reels  up 
antenna    lead.     No.    5    closes    and    secures    chest    for    packing, 
while  No.  4  attends  to  generator,  after  which  they  secure  their 
respective  horses  and   mules  and   spot   the  latter  for  packing. 
Nos.  8  and  9  reel  up  the  counterpoise  and  place  it  in  bottom  of 
bag.     In  their  absence  this  will  be  done  by  Nos.  6  and  7.    The 
chief   of   section   packs    away   antenna   reels   and   secures   pins. 
Nos.  1  and  2,  No.  8  assisting,  pack  generator  mule.     Nos.  6  and 
7,  No.  9  assisting,  pack  chest  mule.     Men,  when  they  find  them- 
selves no  longer  of  assistance  in  packing  mules,  will  promptly 
secure  their  horses,  mount  up,  and  form  column.     No.  3  being 
the  base.    The  section  forms  in  column,  facing  in  the  same  di- 
rection as  when  open  station  was  given. 

THE  WAGON  RADIO  SECTION 

COMPOSITION 

192.  The   wagon    radio   section   is   normally  composed   of  20 
men,  and  one  wagon  radio  set  drawn  by  four  horses.     All  men 
are   individually   mounted   except   the   driver   and   the   engineer, 
who  ride  on  the  wagon. 


146  MILITARY  SIGNAL  CORPS  MANUAL 

The  organization  in  detail  is  as  follows : 
1  section   chief    (sergeant,   first   class). 
3  operators    (1   sergeant,  2  corporals). 
3  mast  men  (1  sergeant,  2  privates,  first  class). 
1  engineer  (corporal). 

8  antenna,  counterpoise  and  guy  men   (1  corporal,  7  pri- 
vates, first  class). 
1  messenger  (private,  first  class). 

1  driver  (private,  first  class). 

2  horseholders  (privates). 

Total,  20. 


FORMATION 

193.  The  mounted  men  of  the  section,  less  the  chief  of  sec- 
tion and  one  horseholder,  are  formed  in  column  of  fours  as  pre- 
scribed in  "The  Soldier  Mounted."  The  wagon  is  posted  so 
that  the  lead  horses  are  2  yards  in  rear  of  the  column  of  fours 
and  in  such  a  position  that  the  pole  of  the  wagon  is  in  pro- 
longation of  the  interval  between  the  numbers  2  and  3  in  the 
mounted  ranks. 


POSTS   AND  DUTIES   OF  INDIVIDUALS 

194.  The  chief  of  section  is  on  the  left  of  the  leading  four, 
two,  or  file,  except  that  when  the  section  is  acting  alone  he  may 
go  where  his  services  are  most  needed.     Beginning  with  No.  1 
on  the  right  of  the  leading  four  and  going  to  the  left,  thence 
beginning  at  the  right  and  going  to  the  left  of  each  succeeding 
four,  the  remaining  mounted  men  of  the  section  are  numbered 
consecutively  from  1  to  17  for  the  purpose  of  describing  their 
duties.     Nos.  1,  2,  and  3  are  operators;  No.  1  being  the  senior 
operator;  No.  4  is  the  messenger;  Nos.  5,  6,  and  7  are  the  mast 
men;  No.  5  being  the  senior  and  in  charge  of  the  mast  detail; 
No.  8  is  a  horseholder;  Nos.  9,  10,  11,  and  12  are  the  antenna 
men;  No.  9  being  the  senior  and  in  charge  of  the  antenna  and 
counterpoise  detail;  Xos.  13,  14,  15,  and  16  are  the  counterpoise 
and  guy  men;  No.  17  is  the  remaining  horseholder  and  marches 
on  the  left  of  the  leaders   except   that   on  the   march  he  may 
ride  in  rear  of  the  wagon. 

THE   WAGON    RADIO   SET 

195.  The  wagon  radio  set  is  carried  on  a  pintle-type  wagon. 
It    consists    of    the    necessary    technical    radio    apparatus,    an 


THE  RADIO  COMPANY  147 

engine,  a  dynamo,  a  jointed  mast,  antenna  and  guy  ropes,  and 
the  counterpoise.  The  technical  radio  apparatus  is  attached 
to  the  front,  and  the  engine  and  dynamo  to  the  rear  element, 
and  electrically  connected  with  the  instruments  by  cable.  On 
the  rear  vehicle  are  also  carried  the  mast,  consisting  of  10 
sections  8  feet  in  length;  the  antenna,  which  has  nine  cords, 
one  of  which  is  the  connecting  cord;  two  sets  of  guy  ropes, 
four  to  each  set ;  and  the  rubber  insulated  wire  counterpoise, 
consisting  of  eight  branches. 

DRILL  OF  THE  SECTION 
Maneuver 

196.  The  section  is  maneuvered  by  the  methods  and  means 
prescribed  for  the  wire  section,  where  applicable. 

To  Open  Station 

197.  The  chief  of  section   indicates  the  location  of  the  sta- 
tion and  commands:   1.  OPEN  STATION. 

At  this  command  the  driver  halts  and  unhitches  his  team. 
The  chief  of  section  moves  the  mounted  men  a  sufficient  dis- 
tance to  be  out  of  the  way  of  the  antenna  and  guy  ropes  when 
the  mast  is  raised  and  dismounts  them.  The  horses  are  turned 
over  to  the  horseholders  (Nos.  8  and  17)  and  the  remaining  men 
proceed  to  unpack  the  wagon,  each  man  assisting  in  unpack- 
ing and  making  ready  that  part  of  the  equipment  which  it  is 
his  duty  to  handle  in  establishing  the  station. 

Nos.  1  and  2  place  the  counterpoise  in  position ;  Nos.  3  and  4 
take  position  on  top  of  the  front  element  of  the  wagon  pre- 
pared to  raise  the  mast;  Nos.  5,  6,  and  7  unpack  the  sections 
of  the  mast  and  place  them  on  the  ground  convenient  to  the 
point  at  which  the  mast  is  to  be  raised;  Nos.  9,  10,  11,  and  12 
unpack  the  antenna  and  pins  or  stakes  and  pay  out  the  antenna 
under  direction  of  the  chief  of  section;  Nos.  13,  14,  15,  and  16 
unpack  and  pay  out  the  two  sets  of  guy  ropes  under  direction 
of  the  chief  of  section. 

As  soon  as  the  top  joint  of  the  mast  is  unloaded,  No.  7  places 
the  top  insulator,  with  antenna  attached,  in  top  of  the  joint 
and  raises  it  vertically  to  Nos.  3  and  4.  He  then  places  the 
remaining  joints  successively  in  place  and  assists  Nos.  3  and  4, 
who  raise  the  mast  vertically.  The  five  smaller  joints  form  the 
upper  part  of  the  mast.  No.  7  also  places  the  guy  rings  in 
place  at  the  top  of  the  fourth  and  seventh  section. 

No.  9  should  be  in  front  of  the  wagon,  with  Nos.  10,  11,  and 
12  in  sequence  to  his  left,  in  a  circle  around  the  mast.  This  will 


148  MILITARY  SIGNAL  CORPS  MANUAL 

bring  No.  11  opposite  No.  9,  and  No.  12  opposite  No.  10.  Each 
man  holds  two  adjacent  antenna  cords,  carries  necessary  pins 
in  his  leggings  and  a  hammer  in  his  belt.  Nos.  13,  14,  15,  and  16, 
the  guy  men,  each  with  an  upper  and  lower  guy  rope,  a  hammer, 
and  necessary  pins  take  position,  in  a  corresponding  manner, 
in  a  smaller  circle  around  the  mast,  No.  13  being  between  No:  9 
and  the  mast.  This  will  bring  No.  15  opposite  No.  13,  and  No. 
16  opposite  No.  14.  As  the  mast  is  being  raised  the  antenna  and 
guy  men,  standing  facing  it,  will  keep  it  vertical  by  proper 
handling  of  the  antenna  and  guys,  under  direction  of  Nos.  5  and 
6.  No.  5  will  direct  9,  11,  13,  and  15,  and  No.  6  will  direct  10, 
12,  14,  and  16.  When  it  is  desired  that  an  antenna  or  guy  be 
pulled  out,  the  command  out  will  be  used,  as  No.  —  OUT. 
When  it  should  be  slacked  off,  the  command  in  will  be  used. 
The  guy  ropes  which  each  guy  man  holds  are  referred  to,  re- 
spectively, as  upper  and  lower. 

When  the  mast  is  up  to  the  required  height  the  chief  of 
section  commands  TIE  IN.  At  this  command  the  guy  men, 
with  the  assistance  of  Nos.  6  and  7,  if  necessary,  drive  pins  in 
the  ground  and  secure  their  guys.  Antenna  men,  with  the  as- 
sistance of  Nos.  6  and  7  or  guymen,  if  necessary  drive  a  pin  in 
the  ground  and  secure  the  proper  antenna  cord.  They  then 
secure  the  remaining  cord  in  a  similar  manner  midway  between 
those  first  placed.  In  doing  this  all  move  to  the  right  from  the 
antenna  cord  first  secured. 

As  soon  as  the  command  tie  in  is  given,  No.  5  makes  the 
proper  connection  for  the  antenna  and  counterpoise,  while 
No.  6  supervises  the  tying  in  and  sees  that  cords  and  ropes  are 
kept  taut. 

198.  As  soon  as  the  driver  unhitches  his  team,  the  engineer 
will  see  that  there  is  sufficient  gasoline  in  the  tank,  oil  in  the 
cups,  water  in  the  proper  receptacles   (if  the  engine  is  water 
cooled),  and  connect  the  dynamo  to  the  instrument  by  means 
of  the  cable  and  generally  make  ready  to  start  the  engine  and 
dynamo. 

When  the  mast  is  up  the  chief  of  section  details  the  opera- 
tors, messengers,  and  guards  for  the  antenna  and  guys,  and 
makes  such  disposition  of  the  remaining  men  as  the  situation 
demands.  If  the  station  is  to  be  maintained  open  any  length 
of  time,  he  also  directs  that  the  picket  line  be  established  or 
the  horses  otherwise  disposed  of. 

The  driver  takes  care  of  his  team. 

To  Close  Station 

199.  At  the  command  close  station,  the  operate*1  removes  the 
antenna   and   counterpoise   connections,  the  guy  men   take   up 


'HIE  RADIO  L'OMl'AXY  14<> 

the  pins  and  hold  the  guys,  each  antenna  man  first  takes  up  the 
pin  and  frees  the  end  of  the  antenna  cord  which  he  last  secured 
and  turns  it  loose,  then  proceeds  to  his  other  antenna  cord, 
pulls  up  the  pin,  and  holds  the  cord  while  the  mast  is  being 
lowered.  The  mast  is  lowered  by  the  same  men  in  the  same 
positions  as  when  being  raised.  Xos.  5  and  6  direct  the  an- 
tenna and  guy  men.  The  counterpoise  men  recover  the  counter- 
poise;  the  engineer  shuts  off  all  valves,  the  driver  brings  his 
team  close  to  wagon,  and  when  the  mast  is  down  hitches  it  to 
the  wagon.  All  men  assist  in  packing  the  equipment  which 
they  unpacked.  When  all  the  apparatus  has  been  securely 
packed  the  chief  of  section  commands  stand  to  horse,  when  all 
men  proceed  to  their  horses  and  obey  this  command.  The 
men  are  then  mounted  and  the  section  formed  by  the  appropri- 
ate commands. 

200.  In  opening  and  closing  station,  all  men  who  have  finished 
the  duty  herein  assigned  to  them  may  be  directed  by  the  chief 
of  section  to  perform  such  other  duties  as  may  be  necessary. 


THE  RADIO   PLATOON 

201.  The  radio  platoon  is  composed  of  two  radio  pack'  sec- 
tions commanded  by  a  lieutenant. 

The  matter  contained  in  "The  Wire  Platoon"  is  applicable  to 
the  radio  platoon,  except  that  the  interval  between  sections  in 
the  order  in  line  is  approximately  22  yards. 

THE  COMPANY 

FORMATION    OF    THE    COMPANY    AND    POSTS    OF    INDIVIDUALS 

202.  The    company    is    formed    and    individuals    therein    arc 
posted  as  prescribed  for  the  wire  company. 

DRILL    OF    THF.    COMPANY 

203.  The  same  movements  in  maneuver  executed  by  the  wire 
company  are  prescribed  for  the  radio  company,  and,  in  so  far  as 
not  entirely  impracticable,  the  same  commands,  methods,  and 
means    are   employed   in   maneuvering  the    latter   as   obtain   in 
maneuvering  the  former.     Wherever  "The  Section"  is  referred 
to  in  the  maneuver  drill  prescribed  for  the  wire  company  it  will 
be  understood  that  for  the  purposes  of  this  section  reference 
to  "The  Pack  Radio  Section"  or  "The  Wagon  Radio  Section," 
as  pertinent,  is  intended. 


150 


MILITARY  SIGNAL  CORPS  MANUAL 


THE  RADIO  COMPANY  151 

EMPLOYMENT  IN  THE  FIELD 

GENERAL 

204.  The  main  equipment  of  each  pack  radio  section  is  one 
pack  radio  set  actuated  by  a  hand  generator,  and  that  of  the 
wagon   radio   section   is   one  wagon   radio   set   actuated  by  an 
engine-driven  dynamo.     Component  parts  of  these  sets  are  as 
indicated  from  time  to  time  in  War  Department  orders.     The 
company   instrument   wagon    carries    a    spare   pack   radio   set. 
The  pack  radio  set  has  a  range  of  20  to  30  miles,  depending  on 
conditions.    The  set  can  be  unpacked,  the  mast  erected,  station 
opened,  and  messages  started  in  2l/2  minutes.    The  wagon  radio 
set  has  a  range  of  150  to  250  miles,  depending  on  conditions. 
The  set  can  be  unpacked,  the  mast  erected,  station  opened,  and 
messages  started  in  10  minutes. 

ASSIGNMENT  OF   SECTIONS  TO  DUTY 

205.  In  general,  the  wagon  set  remains  with  headquarters. 
The  pack  sets  can  be  so  disposed  that  the  division  commander 
can  send  to  and  receive  messages  from  the  divisional  cavalry 
and  other  important  units  with  which  radio  communication  is 
defiired. 

The  field  battalion  at  army  corps  headquarters  can,  if  de- 
sired, make  use  of  the  large  and  more  powerful  motor  truck 
radio  sets  available  there  for  keeping  in  touch  with  the  advanc- 
ing organizations. 

SELECTION   OF   STATION    SITES 

206.  The  selection   of  station    sites  involves  on   the  part   of 
those  charged  with  that  duty  a  suitable  reconnaissance  of  the 
terrain,   according   to   the   principles   laid   down   in   "The   Wire 
Company,"  a  knowledge  of  the  possibilities  and  limitations  ol 
the  station  to  be   erected  and   a  consideration   of  the  tacticai 
needs  and  probable  developments.    The  locality  for  the  station 
will  be  selected  with  as  much  care  as  the  time  available  and 
conditions  will  permit. 

High  open  ground  as  far  from  near-by  hills  as  practicable 
is  to  be  preferred,  due  regard  being  had  for  cover  and  security 
of  the  station.  The  nearer  the  station  is  placed  to  the  com- 
manding officer  or  to  the  headquarters  of  the  command  with 
which  the  section  is  serving,  the  better. 

If  not  impracticable  the  site  selected  should  permit  the  full 
spread  of  antenna  and  guy  ropes.  The  greater  the  spread  of 


152 


MILITARY  SIGNAL  CORPS  MANUAL 


the  antenna  wires,  the  farther  they  are  from  the  ground  and 
the  greater  the  capacity. 

INSTRUCTIONS    FOR    THOSE    IN     CHARGE    OF    FIELD    RADIO     STATIONS 

207.  Be  sure  you  know  the  organization  which  you  are 
serving  and  the  commander  to  whom  you  report  and  are  re- 
sponsible. 

Familiarize  yourself  promptly  with  the  call  letters  and  loca- 
tions of  all  stations  with  which  you  are  in  communication ; 
likewise,  with  the  location  of  your  own  troops  and  the  names 
of  commanders. 

Arrange  for  the  subsistence  of  the  men  and  the  foraging  of 
the  animals. 

Constant  attention  to  instruments  and  minor  repairs  made 
immediately  will  avoid  serious  breakdowns. 

In  receiving,  attention  to  the  insulation  of  the  set  and  the 
mast  from  the  ground  is  very  important. 


AX   ILLUSTRATION  OF  THE   "OPEN    STATION"   OF   A   WAGON   WIRE 
LESS    STATION    TAKEN    UNDER    SERVICE    CONDITIONS 


THE  OUTPOST  COMPANY 

GENERAL  PROVISIONS 
FUNCTION  AND  EMPLOYMENT 

208.  The  general  function  of  the  outpost  company  is  to -ex- 
tend the   lines   of   information   in  the   division   forward  0f  .the 
brigade.     Specifically,   its    normal   function    is    to   furnish    tele- 
phone communication  between  the  infantry  brigade  comrnajtidef 
and    his    regimental    commanders    in    combat.      In    addition,    it 
may  be  called  upon  to  supplement  the  work  -of  the  other  com- 
panies of  the  field  battalion  wherever  the  same  may  be  neces- 
sary or  desirable. 

209.  Conditions  of  employment  will  probably  cause  the  fre- 
quent dispersion   of  the  fractions   of  the  company  among, the 
divisional  units  for  long  periods  of  time.     For  this  reason  the 
personnel   should  be   inculcated  with   the  highest   possible   de- 
gree of  discipline  and  should  have  unquestioned  ability  to  main- 
tain itself  in  the  field. 

,  ORGANIZATION 

210.  The  outpost  company  is  organized  into  a  company  head- 
quarters and  three  platoons. 

The  organization,  in  detail,  is  as   follows: 

1  captain.  1   clerk   (corporal).     , 

4  first   lieutenants.  1  horseshoer. 

1  master   signal   electrician.  2  cooks. 

1  first  sergeant   (sergeant,   first  1  saddler  (corporal). 

class).  1  driver  (private,  first  class.) 

1  mess     and     supply     sergeant  2  buglers  (1  as  guidon,  pri- 

(sergeant).  vates,  first  class). 

1  stable    noncommissioned    offi-  3     platoons  (21  men  each). 

cer  and  farrier  (corporal). 

153 


154 

DUTIES   OF    INDIVIDUALS 

211.  The  duties  of  officers  and  men  in  the  various  grades  are 
identical    with    those    of    similar    grades    in    wire    and    radio 
companies. 

The  captain,  lieutenants,  master  signal  electricians,  first 
sergeant,  buglers,  assistant  platoon  chiefs,  the  chiefs  of  head- 
quarters sections,  and  1  lineman  in  each  platoon  are  individu- 
ally mounted. 

THE  PLATOON 
TACTICAL  EMPLOYMENT 

212.  In  the  outpost  company  the  platoon  is  the  working  unit. 
It  is  specifically  designed,  as  to  personnel  and  materiel,  to  fur- 
nish   practical   telephonic   communication    within    the    infantry 
brigade.     In   the  normal  case  it   connects   the  higher  brigade 
units  in  combat;  in  other  cases  it  furnishes  such  lines  of  in- 
formation as  may  be  ordered  by  the  brigade  commander. 

While  operating,  the  platoon  is  habitually  detached  from  its 
company  and  attached  to  some  other  unit,  normally  the  in- 
fantry brigade.  Under  such  conditions  it  receives  all  orders 
from  and  follows  any  directions  given  by  the  commander  of  the 
unit  to  which  assigned. 

Communication  furnished  by  outpost  platoons  is  not  in- 
tended to  supplant  other  authorized  methods.  It  is  intended 
to  be  supplemental  and  additional  thereto. 

COMPOSITION 

213.  The  platoon  is  composed  of  21  enlisted  men,  commanded 
by  a  first  lieutenant. 

It  consists,  in  detail  of  the  following: 
1  platoon  chief   (first  lieutenant). 

1  assistant  platoon  chief  (sergeant,  first  class,  or  sergeant). 
1  headquarters  section   (4  enlisted  men). 
1  switchboard  section  (4  enlisted  men). 
3  telephone  sections  (4  enlisted  men  each}. 

Total,  1  officer  and  21  enlisted  men. 

The  combat  transportation  of  the  platoon  consists  of  3  pack 
mules. 

214.  The  platoon  chief,  assistant  platoon  chief,  chief  of  head- 
quarters section,  and  one  lineman  belonging  to  the  headquarters 
section  are  individually  mounted.    The  three  pack  mules  of  the 
platoon  are  habitually  attached  one  to  each  of  the  three  tele- 
phone sections,  a  lineman  being  detailed  to  act  as  driver. 


THE  OUTPOST  COMPANY  155 


DUTIES   OF   INDIVIDUALS 

215.  On  detachment  of  the  platoon  from  its  company  and  its 
assignment  with  a  tactical  unit  of  line  troops,  the  duties  of  the 
platoon  chief  assimilate  those  of  a  company  commander.  To 
be  readily  able  to  meet  this  condition  platoon  chiefs  should 
constantly  exercise  administration,  supervision,  and  control 
over  their  commands.  Platoon  unity  of  action  is  paramount 
in  all  outpost  company  training. 

The  assistant  platoon  chief  is  not  attached  to  a  section.  He 
assists  the  platoon  chief  in  the  performance  of  his  duties  and 
is  always  prepared  to  take  command  of  this  unit  if  circum- 
stances render  such  action  necessary. 

The  duties  of  the  several  noncommissioned  officers  and 
enlisted  men  belonging  to  sections  are  described  under  the 
paragraph  relating  thereto. 


NUMERICAL   DESIGNATION    OF    MEMBERS 

216.  The  men  of  the  outpost  platoon,  except  the  platoon 
chief  and  assistant  platoon  chief,  are  numbered  from  1  to  20 
for  the  purpose  of  prescribing  their  positions  and  duties  in  the 
various  drills  and  formations. 

*1.  Sergeant,  section  chief. 

2.  Private,  first  class,  telephone  operator.   iHeadquarters 

3.  Private,  first  class,  telephone  operator,    f       section. 
*4.  Private,  first  class,  lineman. 

5.  Corporal,  section  chief.  "] 

6.  Private,  first  class,  switchboard  operator.    [Switchboard 

7.  Private,  first  class,  switchboard  operator.    (       section. 

8.  Private,  lineman. 

9.  Corporal,  section  chief. 

10.  Private,  first  class,  telephone  operator.    [First  telephone 

11.  Private,  first  class,  lineman.  section. 
f!2.  Private,  lineman. 

13.  Corporal,  section  chief. 

14.  Private,  first  class,  telephone  operator    1       2nd  telephone 

15.  Private,  first  class,  lineman.  section. 
fl6.  Private,  lineman. 

*  Mounted.        f  Mule  Driver. 


156  MILITARY  SIGNAL  CORPS  M.lXl'AL 

17.  Corporal,  section  chief. 

18.  Private,  first  class,  telephone  operator.     I  3rd  telephone 

19.  Private,  first  class,  lineman.  section. 
f20.  Private,  lineman. 


FORMATIONS   AND  POSTS   OF   INDIVIDUALS 

217.  The  habitual  formations  of  the  platoon  are :  In  column 
and  in  line. 

218.  The  formation  in  column  is  that  in  which  the  sections 
in     double  rank  follow  each  other  in  the  order,  headquarters 
section,  switchboard   section,  telephone    sections    in    numerical 
order,  from  front  to  rear.    The  mounted  men  and  mule  drivers 
march  in  column  of  pairs  at  the  rear. 

219.  The  formation  in  line  is  that  in  which  the  sections  are 
abreast  of  each  other  from  right  to  left  in  the  order,  head- 
quarters   section,  switchboard    section,  telephone    sections    in 
numerical   order,   the   dismounted   men   of   the   sections   being 
formed   in    double    rank,   the   mule    drivers    and   mounted   men 
forming  a  third  rank  2  yards  in  rear. 

220.  The   platoon    is   habitually   formed   and   maneuvered  in 
column  ;  the  formation  in  line  is  had  preliminary  to  technical 
operations  and  for  inspection. 

221.  For  the  purpose  of  enlarging  the  front  of  the  column 
and  economizing  road  space,  the  length  of  the  column  may  be 
reduced  by  closing  the  dismounted  men  to  column  of  fours. 

Conversely  to  permit  the  passage  of  obstacles  and  the  trav- 
ersing of  difficult  terrain,  the  front  of  the  column  can  be  con- 
tracted by  forming  both  mounted  and  dismounted  men  in 
column  of  files. 

MANEUVER 
GENERAL  RULES 

222.  On  account  of  the  small  size  of  the  outpost  platoon,  the 
movements  prescribed  for  its  maneuver  are  as  simple  in  char- 
acter and   as   limited   in   number  as   is   possible   to   accomplish 
efficient  handling. 

223.  Whenever  possible,  and  in  all  cases   where  not   other- 
wise prescribed,  the  maneuver  of  the  dismounted  men  will  be 
in    accordance    with    the    principles    laid    down    under    ''Dis- 
mounted   Instruction";    that    of    the    mounted    men    and    mule 
drivers    in    accordance    with    the    principles    of    "Mounted    In- 
struction." 

fMule  driver. 


THE  OUTPOST  COMPANY 


157 


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158 

224.  Wherever  the   term  section  is   used,  it  is  intended  to 
mean  dismounted  section,  or  that  part  of  the  section  included 
in    the    dismounted    rank.     Where    the    term   mounted    man    is 
used,  it  is  intended  to  include  both  men  actually  mounted  and 
mule  drivers. 

To   Form  -the  Platoon 

225.  The  mounted   men  are   marched  to   the   stables  by  the 
assistant  platoon  chief,  who  superintends  the  harnessing  and 
the  saddling.    The  dismounted  men  are  marched  to  the  store- 
rooms by  the  senior  dismounted  noncommissioned  officer  under 
whose  direction  the  equipment  is  procured.     The  chief  of  each 
telephone  section  then  superintends  the  packing. 

The  assistant  platoon  chief  then  forms  the  platoon  in  col- 
umn, verifies,  and  makes  an  inspection  of  it.  He  causes  the 
mounted  men  to  mount,  reports  the  result  of  his  inspection  to 
the  platoon  chief,  and  takes  his  post. 


To    Dismiss    the    Platoon 

226.  The  platoon  chief  commands  :  DISMISS  THE  PLATOON. 

The  platoon  is  marched  to  the  storerooms  by  the  assistant 
platoon  chief.  The  chief  of  each  telephone  section  superin- 
tends the  unpacking.  The  mounted  men  are  then  marched  to 
the  stables  by  the  assistant  platoon  .chief,  who  superintends 
the  unpacking,  unsaddling,  the  disposal  of  horse  and  pack  equip- 
ment, and  the  placing  of  the  animals  in  the  stable  or  on  the 
picket  line.  The  senior  dismounted  noncommissioned  officer  is 
charged  with  the  proper  disposal  of  the  platoon  technical 
equipment. 


227.  Being  at  a  halt :  1.  Forward,  2.  MARCH.     Executed  by 
the  dismounted  rank  in  accordance  with  principles  laid  down 
in  School  of  the  Soldier. 

Executed  by  the  mounted  rank  in  accordance  with  principles 
laid  down  in  paragraph  81. 

The  guide  of  the  platoon  is  its  left  leading  file  unless  other- 
wise announced. 

228.  The    platoon    in    any    formation    may    be    marched    in 
double    time,   the   dismounted    ranks    conforming   to   the   prin- 
ciples  enunciated   in   explanations   of  quick    time    and    double 
time,  the  mounted  rank  putting  their  animals  into  a  slow  trot. 
On  account   of  the   confusion   likely   to   ensue  from  executing 


THE  OUTPOST  COMPANY  159 

this  movement  in  a  mixed  command,  the  same  should  only  be 
employed  where  circumstances  render  rapidity  of  movement 
imperative. 

To  Halt 

229.  Being  in   march,  to  arrest  a  movement:   1.  Platoon,  2. 
HALT. 

Executed  by  dismounted  rank  in  accordance  with  "School 
of  the  Soldier;"  by  the  mounted  rank  as  prescribed  in  para- 
graph 35. 

To  March  to  the  Rear 

230.  1.  Right  (Left)  about,  2.  MARCH. 

At  the  second  command  the  leading  section  changes  direc- 
tion to  the  right  in  accordance  with  principles  laid  down  in 
paragraph  89,  moves  two  paces  forward  in  the  new  direction 
and  again  changes  direction  to  the  right.  The  succeeding  sec- 
tions each  in  turn  conform  to  the  movements  of  the  first, 
executing  identical  movements  on  the  same  ground.  The 
mounted  men  follow  in  column,  each  pair  executing  two  changes 
of  direction  at  the  proper  time  as  prescribed  in  paragraph  89. 

To   March   Obliquely 

231.  1.  Right  (Left)  oblique,  2.  MARCH. 

Executed  simultaneously  by  the  sections  in  accordance  with 
the  principles  of  the  Squad.  Executed  by  the  mounted  men 
as  prescribed  in  paragraph  85. 

To  resume  the  original  direction  :  1.  Forward,  2.  MARCH. 

Executed  as  explained  in  preceding  paragraphs. 

To   Change   Direction 

232.  Being  in  column :  1.  Column  right  (left),  2.  MARCH. 

Executed  by  each  section  successively  according  to  prin- 
ciples of  the  Squad. 

The  mounted  men  follow  in  column,  each  pair  executing  the 
change  of  direction  at  proper  time  as  prescribed  in  paragraph 
89. 

Half  changes  of  direction  are  executed  in  accordance  with 
the  same  principles  substituting  the  command:  Column  half 
right  (left). 

To  Form  Column  to  the  Front  from  Line 

233.  Being  in  line :  1.  Right  by  section,  2.  MARCH. 


160  MILITARY  SIGNAL  CORPS  MANUAL 

The  right  section  moves  straight  to  the  front;  the  other 
sections  execute  section  right,  column  left,  and  follow  the 
leading  section. 

The  mounted  men  move  out  at  the  proper  time  to  take  their 
places  in  column  by  the  shortest  practicable  route. 

This   movement   is   only  executed  from  the   right. 

To  Form  Line  to  the  Front  from  Column 

234.  Being  in  column:  1.  Left  front  into  line,  2.  MARCH,  3. 
Platoon,  4.  HALT,  5.  FRONT. 

At  the  second  command  the  leading  section  moves  straight 
to  the  front,  each  of  the  succeeding  sections  oblique  to  the 
left,  and  when  opposite  its  place  in  line  resumes  original  direc- 
tion of  march.  The  sections  halt  on  arrival  on  the  line  and 
dress  to  the  right  without  command. 

The  mounted  men  move  to  their  places  in  line  by  the  shortest 
practicable  route. 

The  fifth  command  is  given  after  the  completion  of  the  align- 
ment of  both  dismounted  and  mounted  ranks. 

This  movement  is  only  executed  toward  the  left. 


The    Double    Column 

235.  Being  in  column :  1.  Double  column,  2.  MARCH. 

At  the  second  command  the  two  leading  sections  stand  fast 
if  at  a  halt  or  halt  if  in  march.  The  third  and  fifth  sections 
oblique  to  the  left  and  halt  abreast  of  the  second  and  fourth, 
respectively.  The  fourth  section  closes  to  normal  distance  on 
the  second. 

The  mounted  men  close  to  normal  distance  on  the  sections 
and  halt. 

This  movement  is  only  used  in  route  marches  to  economize 
road  space  and  no  other  movements,  except  those  connected 
with  conduct  of  the  march,  are  contemplated  until  the  column 
formation  is  again  resumed. 

236.  Being  in  double  column,  to  form  column  :  1.  Column,  2. 
MARCH. 

At  the  second  command  the  two  leading  sections  take  up 
the  march  if  at  a  halt;  if  marching  they  continue  the  march. 
All  the  other  sections  and  mounted  men  stand  fast  or  halt 
as  the  case  may  be.  The  third  and  fifth  sections  oblique  to 
the  right  in  time  to  follow  the  second  and  fourth  respectively. 
The  fourth  section  moves  forward  to  follow  the  third. 

The  mounted  rank  takes  up  the  march  in  time  to  follow  in 
rear  of  the  dismounted  rank  at  the  proper  distance. 


THE  OUTPOST  COMPANY  161 

The  Single  Column 

237.  Being  in  column :  1.  Single  column,  2.  MARCH. 

At  the  second  command  all  stand  fast  or  halt  if  in  march, 
except  the  right  man  of  the  leading  section.  The  left  lead- 
ing man  obliques  to  the  right  in  time  to  follow  the  leader  at 
the  shortest  practicable  distance.  The  single  column  is  formed 
successively  by  the  other  sections  in  accordance  with  similar 
principles,  each  section  following  its  predecessor  as  closely 
as  possible. 

The  mounted  rank  forms  column  files  in  the  most  conven- 
ient manner  so  as  to  follow  at  normal  distances  in  rear.  The 
order  of  this  column  is  mule  drivers  in  order  of  sections  in 
column  and  mounted  men  in  same  order  as  in  column. 

The  single  column  is  only  used  to  pass  obstacles  or  to  tra- 
verse terrain  where  other  formations  are  unsuitable.  No 
maneuvers  of  the  platoon  except  those  directly  connected  with 
the  conduct  of  the  march  are  contemplated  in  this  formation. 

238.  Being  in  single  column,  to  form  column :  1.  Column,  2. 
MARCH. 

At  the  second  command  the  leading  man  stands  fast  or  halts 
if  in  march.  The  several  sections  are  formed  successively  in 
column  by  the  proper  men  obliquing  to  the  left;  the  sections 
successively  close  to  normal  distances  on  the  leading  section 
and  halt. 

In  the  mounted  rank,  the  mule  drivers  close  to  normal 
distance  and  halt;  the  mounted  men  oblique  to  the  right  and 
halt  in  their  proper  positions  abreast  of  the  drivers. 

To  Align   the   Platoon 

239.  The  platoon  being  in  line  at  a  halt:  If  the  section  on 
the  side  toward  which  the  alignment  is  to  be  made  is  not  in 
proper   position,   the   platoon   chief   establishes   it    in    the   posi- 
tion   desired,    and    commands :    1.    Right    (left),    2.    Dress,    3. 
FRONT.     Executed  by  the  dismounted  rank  according  to  the 
principles  laid  down  in  the  School  of  the  Squad. 

Executed  by  the  mounted  rank  in  accordance  with  principles 
laid  down  in  paragraphs  5  and  80,  the  mounted  man  on  the 
side  toward  which  the  alignment  is  prescribed  establishing 
himself  accurately  in  his  position  2  yards  in  rear  of  the  dis- 
mounted rank. 

The  platoon  chief  aligns  each  rank  separately,  commencing 
with  the  dismounted  rank,  taking  position  for  this  purpose  in 
prolongation  of  the  line,  2  yards  from  and  facing  the  flank 
toward  which  the  alignment  is  made.  After  commanding 
FRONT,  he  resumes  his  post. 


162  MILITARY  SIGNAL  CORPS  MANUAL 

240.  The  alignment   of  the  platoon   in   column   is   conducted 
on  similar  principles.     In  this  case  the  platoon  chief,  in  addi- 
tion to  aligning  the  several  ranks,  sees   that  the  men   column 
cover  accurately  in  file. 

To  Open  and  Close  Ranks 

241.  Being  in  line  at  a  halt:  1.  Open  ranks,  2.  MARCH,  3. 
FRONT. 

Executed  by  the  dismounted  rank  in  accordance  with  the 
principles  of  dismounted  company  instruction,  so  far  as  ap- 
plicable. 

7he  mounted  men  rein  back  the  animals  so  as  to  be  2  yards 
in  rear  of  dismounted  rank  in  its  new  position. 

The  platoon  chief  aligns  the  three  ranks  successively  from 
the  front,  taking  similar  positions  to  those  prescribed  for 
dressing  the  platoon. 

The  command  FRONT  is  given  by  the  platoon  chief  after 
having  aligned  the  ranks  and  taken  position  facing  to  the 
left  4  yards  in  front  of  the  dismounted  rank  directly  in  front 
of  the  right  file.  The  platoon  chief  then  turns  his  horse  to 
the  front. 

242.  Being  in  open  ranks :  1.  Close  ranks,  2.  MARCH. 
Executed  by  the  dismounted  rank  in  accordance  with  prin- 
ciples  of  dismounted   regulations. 

The  mounted  rank  closes  to  normal  distance. 

The  platoon  chief  takes  his  prescribed  post  in   line. 

Route  Order  and  At   Ease 

243.  Marching  in  any  formation  :  1.  ROUTE  ORDER,  or   1. 
AT  EASE. 

Executed  as  prescribed  in  paragraph  9. 

In  route  marches  the  platoon  chief  habitually  marches  on 
the  leeward  side  of  his  platoon  opposite  the  leading  mounted 
man  of  the  platoon. 

TECHNICAL  OPERATION 

The  technical  operation  of  the  outpost  platoon  occurs, 
in  general,  while  it  is  a  detached  unit.  Possible  cases  may 
arise  where  the  platoon  will  operate  in  conjunction  with  other 
signal  units,  but  they  will  be  of  such  rarity  as  to  be  regarded 
as  highly  exceptional.  It  may  be  stated,  therefore,  as  a  guiding 
principle  that  the  outpost  platoon  functions  as  a  unit  in  a 
limited,  but  nevertheless  distinct,  sphere  of  operations. 


THE  OUTPOST  COMPANY  163 

As  before  stated,  the  composition  of  the  platoon  is  based 
upon  furnishing  efficient  telephonic  communication  within  the 
infantry  brigade  in  combat.  The  term  combat  applies  to  all 
phases  of  the  same,  whether  it  be  offensive  or  defensive,  active 
or  passive.  It  can  hardly  be  doubted  that  the  character  of 
the  organization  and  of  its  equipment  is  such  as  will  readily 
lend  itself  to  the  supply  of  lines  of  information  in  many  other 
situations  besides  that  for  which  it  was  primarily  designed. 
In  fact,  in  practically  all  cases  where  troops  in  active  opera- 
tions are  not  in  constant  motion  the  outpost  platoon  can  and 
should  be  utilized  to  advantage. 

Ordinarily  the  platoon  should  be  detached  from  its  com- 
pany and  directed  to  report  to  the  unit,  usually  an  infantry 
brigade,  to  which  it  is  assigned  for  information  service,  as 
soon  as  conditions  pointing  to  early  probable  use  obtain.  As 
soon  as  practicable  after  reporting  for  service,  the  platoon 
commander  should  thoroughly  acquaint  himself  with  the  local 
situation.  He  should  keep  in  constant  touch  with  develop- 
ments and  be  prepared  at  a  moment's  notice  to  lay  any  or  all 
section  lines  in  accordance  with  a  prepared  scheme  and  one 
best  suited  to  the  terrain  to  be  covered. 

On  receiving  an  order  to  lay  certain  lines  of  information, 
a  position  for  the  switchboard  will  be  first  selected.  This 
position  should  generally  be  in  rear  of  the  center  of  the  chain 
of  outlying  stations.  If  at  all  practicable,  the  combat  trans- 
portation and  the  platoon  personnel  should  be  conducted  in- 
tact to  the  switchboard  station  before  commencing  work. 
Whether  this  procedure  can  be  followed  or  not  depends  en- 
tirely on  local  conditions  and  the  decision  at  what  point  the 
platoon  is  to  begin  operations  should  be  decided  by  its  com- 
mander forthwith. 

There  are  no  specific  commands  for  the  technical  handling 
of  the  platoon.  On  arrival  at  the  point  where  wire  laying 
is  to  commence  the  platoon  chief  gives  such  directions  to  the 
various  section  chiefs  as  are  necessary  for  each  to  work 
rapidly  and  intelligently  in  conformity  with  the  general  plan. 
The  technical  equipment  of  the  headquarters  and  switchboard 
sections  is  unpacked  and  turned  over  to  the  personnel  of  these 
sections.  The  switchboard  section  establishes  the  board  at 
the  designated  location  and  the  headquarters  section  at  once 
connects  it  with  general  headquarters.  At  the  same  time  the 
three  telephone  sections,  or  as  many  as  may  be  designated, 
proceed  to  lay  wire  to  connect  their  several  assigned  stations 
to  the  board  and  thus  effect  intercommunication  throughout 
the  system. 


164  MILITARY  SIGNAL  CORPS  MANUAL 

All  stations,  including  the  switchboard  station,  should  be 
selected  so  as  to  be  secure  from  the  view  and  fire  of  the  enemy. 
On  the  other  hand,  the  telephone  sections  should  be  located 
as  close  and  constantly  keep  as  close  as  possible  to  the  com- 
mander of  unit  for  whose  use  they  are  installed.  The  fact  that 
the  telephone  is  an  instrument  for  the  commander's  personal 
use  should  never  be  lost  sight  of.  It  will  be  frequently  dim- 
cult  to  reconcile  the  two  above  conditions,  but  the  same 
should  be  done  whenever  possible. 

The  laying  of  the  lines  should  always  be  done  with  a  view 
to  successful  maintenance.  They  should  be  as  short  and  direct 
as  is  possible  consistent  with  security  from  hostile  view  and 
fire.  They  should  avoid,  if  practicable,  crossing  or  traversing 
routes  of  probable  use  by  line  troops.  If  this  be  impracticable, 
arrangements  should  be  made  for  their  protection  at  these 
points.  When  the  lines  are  in  service  the  operators  will  be 
constantly  "on"  their  instruments,  and  trouble  of  any  kind 
should  be  detected  almost  coincident  with  its  occurrence.  Im- 
mediate effort  should  be  made  by  all  concerned  to  effect  its 
early  removal. 

Cases  will  no  doubt  arise  where  the  use  of  the  switchboard 
will  be  unnecessary  or  inadvisable.  These  cases  should  be 
readily  apparent  to  the  platoon  chief,  and  necessary  orders 
should  be  given  to  lay  independent  lines. 

The  telephone  stations  keep  intimate  contact  with  their  unit 
commanders  at  all  times.  The  general  procedure  in  operating 
the  line  will  be  to  have  the  telephone  operator  send  a  call  for 
the  individual  wanted  to  come  to  the  telephone.  The  matter 
of  time  makes  short  distances  imperative.  All  communications 
over  outpost  lines  should  be  by  personal  conversation  of  the 
officers  concerned.  Any  other  method  of  transmitting  informa- 
tion over  telephone  lines  is  unnecessarily  slow,  generally  inac- 
curate, and  frequently  dangerous. 

The  personnel  of  the  station  sections  should  be  intimately 
acquainted  with  the  several  unit  commanders  and  their  staffs. 
This  is  necessary  in  finding  their  proper  locations'  when 
initially  laying  the  line,  and  especially  so,  if,  as  will  frequently 
be  the  case,  the  exact  location  of  the  unit  to  be  connected  is 
in  doubt.  Unless  this  personal  element  obtains  valuable  time 
may  often  be  lost  by  failures  to  find  the  proper  headquarters, 
in  taking  erroneous  routes,  and  causing  wire  to  be  recovered 
and  relaid. 

When  a  change  in  the  system  is  necessary,  the  platoon 
chief  will  give  directions  how  the  same  shall  be  effected.  Minor 
changes  can  usually  be  made  by  lengthening  or  shortening  one 
or  more  lines  in  use.  In  extended  changes  it  will  probably 
be  best  to  recover  all  wire,  assembling  the  platoon  at  the 


THE  OUTPOST  COMPANY  165 

switchboard,  and  project  an  entirely  new  system  in  accordance 
with  the  new  plan. 

The  improvised  expedients  possible  with  the  outpost  platoon 
are  innumerable.  In  no  branch  of  signal  work  will  the  re- 
sourceful officer  find  a  larger  field  than  in  this  work;  in  no 
branch  will  practical  experience  be  of  more  value. 

Uninterrupted  communication  between  the  units,  despite 
all  conditions,  is  the  goal  to  be  striven  for,  and  the  subaltern 
who  attains  it  will  have  found  that  he  has  solved  a  problem 
more  difficult  than  those  which  usually  confront  far  higher 
commanders. 

THE  SECTIONS 
TYPES  OF  SECTIONS 

The  outpost  platoon  is  composed  of  five  sections,  namely, 
one  headquarters  section,  one  switchboard  section,  and  three 
telephone  sections. 

The  headquarters  section  does  not  derive  its  name  from 
the  fact  that  it  is  the  headquarters  of  the  platoon,  for  such  Is 
by  no  means  the  case.  It  is  so  termed  because  its  normal  sta- 
tion is  at  the  brigade  or  other  unit  headquarters  to  which 
the  platoon  is  attached. 

The  switchboard  section  derives  its  name  from  the  character 
of  duty  it  is  designed  to  perform.  The  operation  and  main- 
tenance of  the  switchboard  is  its  primary  function.  In  addi- 
tion, it  performs  such  duties  of  line  maintenance  as  may  be 
necessary. 

The  telephone  sections  are  so  called  because  they  are 
normally  designed  to  operate  the  telephone  stations  at  the  sev- 
eral subsidiary  units.  In  addition,  they  install  and  maintain 
the  lines  necessary  between  their  variously  assigned  stations 
and  the  switchboard. 

THE    HEADQUARTERS     SECTION 

The  personnel  consists  of  one  sergeant,  chief  of  section 
(mounted),  one  private,  first  class,  lineman  (mounted),  and 
two  privates,  first  class,  telephone  operators. 

The  technical  equipment  includes  one  telephone,  one  breast 
reel,  and  one  half-mile  outpost  wire,  together  with  certain 
miscellaneous  articles  necessary  for  the  installation  and  main- 
tenance of  the  line  and  the  operation  of  one  telephone  station. 

The  mounts  of  the  section  constitute  a  properly  located 
reserve  calculated  to  afford  rapid  assistance  to  any  of  the  other 
sections  wherever  occasion  should  require  it. 


166  MILITARY  SIGX.IL  CORPS  MANUAL 

The  specific  duties  of  the  various  individuals  of  the  sec- 
tion are  generally  described  by  the  character  of  their  titles. 
In  general  all  perform  any  duties  necessary  to  rapid  and 
efficient  transmission  of  information.  This  includes  any  neces- 
sary messenger  service  in  connection  with  the  operation  of 
the  line,  provided  the  same  can  not  be  promptly  performed  by 
other  troops. 

The- small  amount  of  wire  assigned  to  this  section  pre- 
supposes that  the  length  of  line  between  unit  headquarters  and 
the  switchboard  will  be  very  short.  It  is  not  expected  that  it 
will  ordinarily  exceed  a  few  hundred  yards.  For  this  reason, 
the  headquarters  and  switchboard  sections  will  frequently  be 
able  to  perform  their  combined  duties  as  a  single  group,  this 
permitting  a  large  platoon  reserve  for  the  support  of  other 
sections  of  the  line,  if  same  should  be  required. 

THE    SWITCHBOARD    SECTION 

The  personnel  consists  of  one  corporal,  chief  of  section, 
two  privates  (first  class),  switchboard  operators,  and  one  pri- 
vate (lineman). 

The  technical  equipment  includes  one  field  switchboard 
and  such  miscellaneous  articles  as  are  necessary  for  the  opera- 
tion of  the  switchboard  station  and  the  maintenance  lines 
contiguous  thereto. 

There  are  no  mounts  or  pack  animals  attached  to  this,  sec- 
tion, and  it  is  not  expected  to  lay  wire.  On  account  of  its 
position,  one  having  direct  access  to  all  lines,  it  will  be  pe- 
culiarly susceptible  to  the  early  location  of  line  trouble  in 
the  system,  and  prompt  attention  should  be  given  in  every  in- 
stance toward  removing  it. 

The  specific  duties  of  individuals  are,  as  with  the  head- 
quarters section,  generally  described  by  the  character  of  their 
titles.  In  general  the  duties  of  the  entire  section  are  em- 
braced under  two  heads,  namely,  the  operation  of  the  switch- 
board and  the  prompt  removal  of  trouble  occurring  on  any 
radiating  line.  Duties  will  be  performed  by  various  members 
of  the  section  in  such  a  way  as  to  best  accomplish  these  ends. 

The  location  of  the  switchboard  is  of  primary  importance 
in  the  installation  and  operation  of  the  line.  This  will  be  al- 
ways done,  if  at  all  practicable,  by  the  platoon  chief.  He 
takes  into  consideration  the  tactical  situation,  the  features  of 
the  terrain,  and  the  present,  and  probable  future,  positions  of 
headquarters  and  the  various  subordinate  units  to  be  con- 
nected. The  possession  of  a  good  map  and  a  position  affording 
a  clear  view  of  the  surrounding  country  are  indispensable  re- 
quisites to  the  intelligent  selection  of  this  position. 


THE   OUTMOST  COMl'.IXr  167 

THE     TELEPHONE     SECTIONS 

These  sections  are  designed  to  furnish  lines  and  telephone 
stations  for  three  subordinate  unit  headquarters  by  con- 
necting same  to  general  headquarters  through  the  switch- 
board. The  personnel,  materiel,  and  transportation  of  the 
telephone  sections  are  identical. 

The  personnel  of  a  telephone  section  consists  of  one  cor- 
poral, chief  of  section;  one  private,  first  class,  telephone  opera- 
tor; one  private,  first  class,  lineman;  and  one  private,  lineman. 
The  latter,  in  addition  to  his  other  duties,  acts  as  packer  and 
mule  driver. 

The  materiel  of  the  section  consists  of  one  telephone,  one 
breast  reel,  and  2  miles  of  outpost  wire,  together  with  certain 
miscellaneous  articles  necessary  for  the  installation  and  main- 
tenance of  the  line,  and  the  operation  of  one  telephone  station. 

The  platoon  combat  transportation,  the  three  pack  mules, 
is  habitually  attached  to  the  three  telephone  sections.  These 
animals  will  transport  the  entire  technical  equipment  of  the 
platoon  until  the  commencement  of  active  operations.  At  this 
time  materiel  belonging  to  the  headquarters  and  switchboard 
sections  will  be  removed  from  the  packs  and  transferred  to  the 
personnel  of  these  sections.  Thereafter  one  pack  animal  will 
accompany  each  telephone  section  to  its  assigned  station  and 
remain  with  it  throughout  action,  unless  good  reasons  exist 
for  the  contrary. 

As  with  the  other  sections,  the  character  of  duty  per- 
formed by  the  individuals  of  the  telephone  section  is  indicated 
by  their  titles.  In  general  the  duties  performed  by  the  mem- 
bers of  the  section  are  similar  to  those  prescribed  for  mem- 
bers of  the  headquarters  section. 

Each  telephone  section  is  expected  to  install  and  main- 
tain a  line  from  the  switchboard  to  a  certain  designated  sub- 
ordinate unit  headquarters,  and  to  operate  a  telephone  station 
thereat.  To  effect  this  connection  the  wire  furnished  is  ex- 
pected in  all  ordinary  cases  to  be  ample  for  this  purpose.  The 
section  will  follow  with  its  line  all  movements  of  the  head- 
quarters to  which  attached,  keeping  intimate  connection  there- 
with and  utilizing  its  own  wire  as  far  as  possible.  Where 
necessary  and  practicable,  improvised  lines  will  be  employed. 
Frequent  reports  will  be  made  by  chiefs  of  sections  to  the 
platoon  chief  as  to  location  of  the  section  station,  amount  of 
unused  wire  on  hand,  anticipated  movements,  and  the  prac- 
ticability of  employing  existing  lines  for  purposes  of  com- 
munication. 


168 

So  far  as  is  practicable,  after  a  section  station  is  once 
opened,  the  lines  of  the  telephone  sections  will  be  kept  in  con- 
stant communication  with  switchboard.  In  changing  the  loca- 
tion of  the  station  timely  arrangements  should  be  made  for 
extending  the  line  and  the  telephone  removed  therefrom  only 
for  the  shortest  time  compatible  with  removal  to  the  new  site. 


THE  COMPANY 
FORMATION  OF  THE  COMPANY 

244.  The   habitual    formations   are:   The    order   in   line,   the 
order  in  section  column. 

245.  The  order  in  line  is  that  in  which  the  platoons,  each  in 
column  of  sections,  are  formed  abreast  of  each  other  in  their 
numerical  order  or  the  reverse  order  from  right  to  left.     The 
interval  between  the  platoons  is  27  yards. 

246.  The  order  in  section  column   is   that   in   which  the   pla- 
toons, each  in  column  of   sections,  follow   each  other  in  their 
numerical  order  or  the  reverse  order,  from  front  to  rear.    This 
distance  between  the  platoons  is  4  yards. 

POSTS    OF    INDIVIDUALS 

247.  The  captain  in  the  order  in  line  is  8  yards  in  front  of 
the  company  opposite  its  center.     In  the  order  in  section  col- 
umn, he  is  opposite  its  center  and  16  yards  from  the  flank.     In 
column  the  captain  is  on  the  left  when  the  first  platoon  leads 
and  on  the  right  when  the  column  is  reversed. 

The  platoon  chiefs  in  both  formations  are  posted  4  yards 
to  the  left  and  abreast  of  the  leading  file  of  their  platoons. 

The  first  lieutenant  not  commanding  a  platoon,  the  first 
sergeant,  and  master  sigrlal  electrician  occupy  similar  posi- 
tions in  both  formations  with  reference  to  the  first,  second,  and 
third  platoons,  respectively.  Each  is  posted  on  the  right  flank 
of  the  respective  platoon,  opposite  the  center  and  2  yards 
therefrom. 

The  guidon  in  line  is  abreast  of  the  leading  rank  of  the 
company  and  2  yards  from  the  flank  toward  which  the  guide 
has  been  announced ;  in  section  column  abreast  of  and  2  yards 
to  the  right  of  the  leading  rank  of  the  leading  section. 

The  buglers,  or  bugler  not  acting  as  guidon,  follow  2  yards 
in  rear  of  the  captain. 

The  dismounted  men  attached  to  company  headquarters  do 
not  take  part  in  company  maneuvers,  except  when  assigned  to 
duty  in  platoons.  Otherwise  they  are  present  only  with  field 


THE  OUTPOST  COMPANY 


169 


25  YDS. 


CAPTAIN 
COMPANY  IN    COLUMN 


LEGEND 

4  CAPTAIN 

•  FIRST  LIEUTENANT 

b  M.S.E. 

6  FIRST  SERGEANT 

Q  BUGLER 

El  GUIDON 


2  YDS 


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COMPANY   IN   LINE 

THE  OUTPOST  COMPANY 


ZYDS. 


170  MILITARY  SIGNAL  CORPS  MANUAL 

and  combat   transportation,  taking   such   posts  with   it   as   are 
assigned  them  by  the  captain.    ' 


MANEUVER 

General  Rules 

248.  The  rules  for  the  maneuver  of  the  platoon  apply  to  the 
company. 

249.  The  guide  of  the  company  in   line   is   the  guide  of  the 
platoon    on    the    side    of    the    guide.      In    section    column    it    is 
the  guide  of  the  leading  platoon. 

250.  During  an  oblique  march  the  guide  of  the  company  is, 
without  indication,  the  guide  of  the  platoon    on    the    side    to 
which   the  oblique  is  made. 

251.  The  guidon  conducts  himself  as  prescribed  for  maneu- 
ver of  wire  or  radio   companies. 

252.  In   all  maneuvers   resulting  in   a   formation   in   line  the 
company  is   either  halted  at  the  completion  of  the  formation, 
or  the  guide  is  announced  if  the  march  is  to  be  continued. 

253.  Platoon   chiefs    repeat   such    preparatory   commands    as 
are  to  be  immediately  executed  by  their  platoons.     They  give 
only   such   commands   of   execution   as   are  necessary  to   cause 
their  platoons  to  function  properly  in  company  maneuver. 


To  Form  the  Company 

254.  The  company  is  formed  dismounted  by  the  first  ser- 
geant after  which  he  commands :  By  platoon,  FALL  OUT. 
The  procedure  outlined  in  paragraph  225  is  followed  by  each 
platoon.  Each  platoon  is  then  minutely  inspected  by  its  assist- 
ant chief. 

The  first  sergeant  forms  the  company  in  line  and  takes  his 
post. 

Each  platoon  chief,  having  received  the  report  of  his  assist- 
ant platoon  chief,  makes  a  general  inspection  of  his  platoon 
and  commands :  REST. 

Upon  the  approach  of  the  captain  the  platoon  chiefs  call 
their  platoons  to  attention,  and  as  soon  as  the  captain  takes 
his  place  in  front  report  in  succession  from  right  to  left: 
(SUCH)  PLATOON  IN  ORDER,  SIR;  or  if  anything  is  miss- 
ing or  out  of  order  they  so  report. 

As  soon  as  the  platoon  chiefs  have  reported,  the  first  ser- 
geant reports  to  the  captain  as  prescribed  in  forming  the  com- 
pany dismounted. 


THE  OUT  POST  COMPANY  171 

The  lieutenant  not  assigned  as  platoon  chief  and  the  master 
signal  electrician  take  their  posts  on  the  approach  of  the 
captain. 

To  Dismiss  the  Corrpany 

255.  The  captain  commands :  DISMISS  THE  COMPANY. 

The  lieutenants  and  master  signal  electrician  fall  out.  The 
first  sergeant  takes  charge  of  the  company  and  commands : 
By  platoon,  FALL  OUT.  The  platoons  are  then  dismissed  as 
prescribed  in  paragraph  226. 

To  Align  the  Company 

256.  The  company  being  in  line  at  a  halt. 

If  the  platoon  on  the  side  toward  which  the  alignment  is  to 
be  made  is  not  in  proper  position,  the  captain  establishes  it  in 
the  position  desired  and  commands  :  1.  Right  (left),  2.  DRESS, 
3.  FRONT. 

At  the  command  DRESS,  the  other  platoons  move  forward 
or  backward,  the  leading  dismounted  rank  aligning  itself  to- 
ward the  right;  both  dismounted  and  mounted  men  turn  their 
heads  to  the  right  and  dress  on  the  corresponding  elements  in 
the  platoon  on  their  right. 

The  captain  aligns  the  leading  dismounted  and  mounted 
ranks  of  all  the  platoons,  taking  position  for  this  purpose  in 
prolongation  'of  the  line,  2  yards  from  and  facing  the  flank 
toward  which  the  alignment  is  made.  After  commanding 
FRONT,  he  resumes  his  post. 

To  March  to  the  Front 

257.  Being  at  a  halt:  1.  Forward,  2.  MARCH. 

Executed  simultaneously  by  all  the  platoons  as  prescribed 
in  paragraph  227.  All  the  platoons  move  straight  to  the 
front,  taking  care  to  maintain  their  proper  relative  positions 
in  the  formation. 

258.  The  principles    of    paragraph  228  relative  to  movements 
in  double  time  in  the  platoon  apply  to  the  comp-ny. 

To  Halt 

259.  Being  in  march :  1.  Company,  2.  HALT. 

Executed  by  each  platoon  as  prescribed  in  paragraph  229 
all  platoons  stopping  simultaneously  but  not  suddenly. 

To  March  to  the  Flank 

260.  1.  By  the  right  (left)  flank,  2.  MARCH. 


172  MILITARY  SIGXAL  CORPS  MAXl'AL 

Executed  simultaneously  by  each  platoon  making  a  change 
of  direction  as  prescribed  in  paragraph  232. 

To  March  to  the  Rear 

261.  1.  Right  (left)  about,  2.  MARCH. 

Executed  simultaneously  by  each  platoon  as  prescribed  in 
paragraph  230. 

To  March  Obliquely 

262.  1.  Right  (left)  oblique,  2.  MARCH. 

Executed  by  each  platoon  as  prescribed  in  paragraph  231. 

To  Change  Direction 

263.  Being  in  column:  1.  Column  right  (left),  2.  MARCH. 

Executed  successively  by  the  platoons  in  accordance  with 
paragraph  232,  each  platoon  chief  giving  the  command  for  his 
platoon  to  change  direction  on  the  .same  ground  as  the  one 
preceding  it. 

264.  Being  in   line:    1.  Company  right  (left),    2.  MARCH,    3. 
Company,  4.  HALT. 

The  right  platoon  changes  direction  to  the  right,  the  other 
platoons  are  conducted  by  the  shortest  line  to  their  places 
abreast  of  the  first. 

The  fourth  command  is  given  when  the  right  platoon  has 
advanced  the  desired  distance  in  the  new  direction;  that  platoon 
halts;  the  others  halt  successively  on  arriving  on  the  line. 

To  Close  or  Extend  Intervals 

265.  On   (such)  platoon,    2.    To   (so    many    yards),    3.    Close 
(extend)  intervals,  4.  MARCH,  5.  Company,  6.  HALT. 

The  indicated  platoon  moves  straight  to  the  front,  the 
other  platoons  oblique  toward  or  away  from  the  indicated 
platoon,  and  move  to  the  front  when  at  proper  interval. 

The  sixth  command  is  given  when  the  directing  platoon  has 
advanced  sufficient  distance  to  permit  the  proper  execution  of 
the  movement  by  the  other  platoons ;  it  halts ;  the  other  pla- 
toons halt  successively  on  arrival  in  line. 

To  Form  Column  from  Line 

TO  THE  FRONT 

266.  Being  in  line :  1.  Right  (left),  by  platoon,  2.  MARCH.  . . 

The  right  platoon  moves  straight  to  the  front  if  marching; 
if  at  a  halt  it  takes  up  the  march.  The  other  platoons,  in 


THE  OUTPOST  COMPANY  ,  173 

turn,  execute  column  right  and  follow  in  column  at  4  yards 
distance. 

TO  THE  FLANK 

267.  Executed  as  prescribed  in  paragraph  260. 

To  Form  Line  from  Column 

TO  THE  FRONT 

268.  1.  Right  (left)  front  into  line,  2.  MARCH,  3.  Company, 
4.  HALT. 

The  leading  platoon  moves  straight  to  the  front.  Each  pla- 
toon in  rear  executes  column  half  right.  When  opposite  its 
place  in  line  it  executes  column  half  left,  and  moves  to  its 
place  in  line. 

The  fourth  command  is  given  when  the  directing  platoon 
has  advanced  the  desired  distance;  it  halts;  the  other  platoons 
halt  successively  on  arrival  at  their  places  in  line. 

TO  THE  FLANK 

269.  On  right  (left)  into  line,    2.  MARCH,    3.  Company,    4. 
HALT. 

The  leading  platoon  executes  column  right  and  moves 
straight  to  the  front  in  the  new  direction.  The  platoons  in 
rear  continue  to  march  straight  to  the  front;  each  passes  be- 
yond the  platoon  directly  preceding  it,  and  when  opposite  the 
right  of  its  place  executes  column  right  and  proceeds  to  its 
place  in  line. 

The  fourth  command  is  given  when  the  directing  platoon  has 
advanced  the  desired  distance  in  the  new  direction ;  it  halts ; 
the  other  platoons  halt  on  arrival  successively  at  their  proper 
places  in  line. 

270.  1.  Right  (left)  into  line,  2.  MARCH,  3.  Company,  4.  HALT. 
The    leading    platoon    executes    column    right    and    moves 

straight  to  the  front  in  the  new  direction.  The  platoons  in  rear 
continue  to  march  straight  to  the  front  until  each  is  at  the 
right  of  its  place  in  line,  at  the  prescribed  interval  from  the 
preceding  platoon ;  each  then  executes  column  right  and  pro- 
ceeds to  its  place  in  line. 

The  fourth  command  is  given  when  the  directing  platoon 
has  advanced  the  desired  distance  in  the  new  direction:  it 
halts ;  the  other  platoons  halt  successively  on  arrival  at  their 
places  in  line. 


174  ,    MILITARY  SIGNAL  CORPS  MANUAL 

This  movement  is  intended  to  be  used  to  form  line  with 
contracted  intervals  and  therefore  the  interval  between  pla- 
toons desired  should  be  interpolated  in  the  preparatory  com- 
mand. 

The  Double  Column 

271.  Formed  simultaneously  by  each  platoon   as  prescribed 
in  paragraphs  235  and  236. 

The  platoon  "chiefs  of  the  rear  platoons  close  their  platoons 
on  the  preceding  element  as  soon  as  the  double  column  is 
formed. 

The  Single  Column 

272.  This   movement   is   not   usually   executed   by  the   com- 
pany.    If  desired,  however,  it  can  be   executed  as   prescribed 
in  paragraphs  237  and  238. 

To  Form  the  Platoons  in  Line 

273.  Being  in  line  of  column :  1.  Platoons,  2.  Left  front  into 
line,  3.  MARCH,  4.  Company,  5.  HALT,  6.  FRONT. 

Executed  at  the  third  command  simultaneously  by  each 
platoon  as  prescribed  in  paragraph  234. 

The  lieutenant  not  commanding  a  platoon,  the  first  sergeant, 
and  the  master  signal  electrician  take  post  4  yards  in  rear  of 
the  center  of  the  respective  platoons. 

The  sixth  command  is  given  after  the  completion  of  the 
alignment  of  the  dismounted  and  mounted  ranks  of  the  com- 
pany. 

This  movement  is  only  executed  to  the  left. 

To  Form  Line  or  Column 

274.  1.  Platoons,  2.  Right  by  sections,  3.  MARCH. 

Executed  simultaneously  by  each  platoon  as  prescribed  in 
paragraph  233. 

This  movement  is  only  executed  from  the  right. 

To  Open  and  Close  Ranks 

275.  Being  in   line,  or  in   column,  with   platoons   in   line   at 
a  halt :  I.  Open  ranks,  2.  MARCH,  3.  FRONT. 

Executed  by  each  platoon  simultaneously  as  prescribed  in 
paragraph  241.  The  file  closers  conform. 


THE  OUTPOST  COMPANY  175 

The  captain  aligns  the  ranks  of  the  company  successively 
from  front  to  rear  from  similar  positions  to  those  described 
for  dressing. 

The  command  FRONT  is  given  by  the  captain  after  having 
aligned  all  the  ranks  and  taken  position  facing  to  the  left  4 
yards  in  front  of  the  dismounted  rank  of  the  right  or  leading 
platoon,  and  directly  in  front  of  its  right  file.  The  captain 
then  turns  his  horse  to  the  front. 

276.  Being  at  open  ranks:  1.  Close  ranks,  2.  MARCH. 
Executed  simultaneously  by  each   platoon   as  prescribed   in 

paragraph  242. 

Route  Order  and  at  Ease 

277.  Executed   as   prescribed   for   dismounted   and   in  para- 
graph 9. 

In  route  marches,  the  captain  marches  8  yards  in  front 
of  the  leading  element,  followed  at  2  yards  by  the  bugler  and 
guidon,  the  latter  on  the  right.  Platoon  chiefs  march  as  pre- 
scribed in  paragraph  243.  File  closers  march  where  the  captain 
directs.  The  company  instrument  wagon  marches  in  rear  of 
the  column. 

EMPLOYMENT  IN  .THE  FIELD 

The  employment  of  the  outpost  company  in  the  field  in- 
cludes the  functioning  of  its  several  platoons  in  performing- 
such  duties  as  may  be  directed  by  the  field  battalion  com- 
mander. 

The  detachment  of  any  element  or  elements  of  the  com- 
pany when  necessity  for  the  same  arises,  occurs  at  the  direc- 
tion of  the  battalion  and  by  the  order  of  the  company  com- 
mander. The  company,  at  all  times,  acts  as  administrative 
headquarters  for  all  of  its  units  whether  attached  or  detached. 
This  matter  will  be  attended  with  some  difficulty  if  the  units 
be  widely  scattered  as  may  frequently  happen.  The  procedure 
is  inevitable,  however,  from  the  fact  that  the  company  func- 
tions wholly  in  the  dispersion  of  its  elements. 

Besides  the  conduct  of  administration,  the  company  head- 
quarters will  furnish  such  assistance  to  the  working  units  as 
may  be  necessary  for  the  efficient  performance  of  their  duties 
at  all  times  and  under  all  circumstances. 

Detached  signal  units  usually  mess  with  line  troops  with 
whom  they  are  assigned  for  duty.  Where  this  method  is  for 
any  reason  impracticable,  necessary  arrangements  for  separate 
subsistence  must  be  made  by  the  company,  if  necessary,  as- 
sisted by  the  battalion  commander. 


176  MILITARY  SIGNAL  CORPS  MANUAL 

Company  headquarters  assists  the  several  detached  platoons 
by  furnishing  such  reserve  personnel  and  materiel  as  may  be 
practicable. 

The  limited  quota  of  company  headquarters  will  necessarily 
restrict  the  number  of  reserve  personnel  which  at  any  time 
can  be  spared  for  detachment  therefrom. 

Some  reserve  personnel,  however,  can  and  should  be  sup- 
plied by  it,  if  called  upon.  Moreover,  if  all  the  working  units 
are  not  detached  at  the  same  time,  provision  can  be  made  to 
temporarily  re-enforce  active  units  from  those  inactive.  As 
the  platoon  and  the  several  sections  therein  are  made  large 
enough  to  furnish  their  own  reserves,  depletion  beyond  the 
safety  limit  should  be  discovered  in  ample  time  to  requisition 
and  secure  the  needed  reserve  personnel  from  the  nearest  point 
at  which  they  are  readily  obtainable.  Furthermore,  the  tempo- 
rary presence  of  one  or  more  of  the  specially  skilled  members 
of  the  headquarters  staff,  such  as  the  horseshoer  or  saddler, 
will  not  infrequently  be  of  incalculable  benefit  if  promptly  sup- 
plied to  detached  units  when  needed.  Close  touch  should, 
therefore,  be  had  at  all  times  with  the  working  units  looking 
to  the  supply  of  this  character  of  aid  if  the  same  should  be 
required. 

A  reasonable  amount  of  reserve  materiel  is  carried  upon 
the  company  instrument  wagon.  This  materiel  includes  not 
only  a  reserve  supply  of  all  materiel  used  by  the  outpost  pla- 
toon, but  in  addition,  extra  tools  and  certain  special  articles, 
the  need  for  which,  while  infrequent,  is  at  times  imperative. 
The  need  for  any  of  this  materiel  should  be  readily  and  quickly 
apparent  at  company  headquarters  through  unfailing  channels 
of  contact  with  its  working  units,  and  no  delay  should  be 
permitted  in  proper  supply. 

The  technical  operation  of  the  working  units  is  described 
under  the  platoon.  The  general  function  of  the  company  is 
the  support,  maintenance,  and,  when  necessary,  the  co-ordina- 
tion of  the  work  of  these  units  when  employed  in  the  service 
of  information. 


THE  FIELD  BATTALION 

ORGANIZATION  OF  THE  BATTALION 

278.  The  headquarters  of  a  field  battalion  consists  of  the  fol- 
lowing: 

One  battalion  commander   (major). 

One  battalion  adjutant  and  supply  officer  (first  lieutenant). 

One  sergeant  major,  assistant  to  the  adjutant   (sergeant, 

first  class). 
One  clerk  (sergeant). 
One  color  sergeant   (sergeant). 
Four  orderlies   (privates,  first  class). 
One  driver,  for  shop  wagon  (private,  first  class). 
The   supply  detachment  of  a  field  battalion  consists  of  the 
following: 

One  battalion  supply  sergeant    (sergeant,   first   class). 
Five  drivers,  for  field  train  wagons  (privates,  first  class). 

POSTS  OF  INDIVIDUALS 

279.  At  ceremonies  the  major  is  30  yards  in  front  of  his  bat- 
talion, opposite  the  center.    On  other  occasions  he  places  him- 
self  where   he   can   most   readily   observe   and    direct    his    bat- 
talion.   The  commissioned  staff  is  posted  2  yards  in  rear  of  the 
major;  the  noncommissioned  staff  and  the  orderlies,  similarly 
formed,  2  yards  in  rear  of  the  commissioned  staff.    The  supply 
detachment  is  with  the  field  train. 

FORMATION    OF    THE   BATTALION 

280.  The  normal  formations  of  the  battalion  are  the  order 
in  line  and  the  order  in  section  column. 

177 


178  MILITARY  S1GXAL  CORPS  MAX  UAL 

281.  In  the  order  in  line  the  companies  of  the  battalion,  each 
in  the  order  in  line  are  formed  abreast  of  each  other  in  the 
order,  from  right  to  left,  outpost  company,  wire  company,  and 
radio  company.     The  interval  between  companies  is  30  yards. 
If  the  battalion  be  formed  with  closed  intervals,  the  interval 
between  companies  is  15  yards. 

282.  In  the  order  in  section  column  the  companies  of  the  bat- 
talion, each  in  the  order  in  section  column,  follow  each  other 
in  the  order  given  in  the  preceding  paragraph.     The  distances 
between    companies   are   such   as   would   result   from  the   com- 
panies moving  simultaneously  by  the  flank  from  the  order  in 
line. 

TO    FORM    THE    BATTALION 

283.  To  form  the  battalion  in  line,  the  adjutant  causes  ad- 
jutant's call  to  be   sounded;  the  adjutant  and  sergeant   major 
proceed  to  the  selected  ground  and  post  themselves  facing  each 
other  a  few  yards  outside  the  points  where  the  right  and  left 
of  the  right  company  of  the  battalion  are  to  rest. 

The  companies  approach  the  line  from  the  rear  and  are 
posted  in  succession  from  right  to  left  by  their  captains,  so 
that  the  front  rank  will  be  on  the  line  established  by  the  adjut- 
ant and  sergeant  major.  After  halting  his  company,  each  cap- 
tain aligns  it  toward  the  right. 

When  the  company  that  arrives  first  on  the  line  has  been 
established,  the  sergeant  major  joins  the  battalion  noncommis- 
sioned staff. 

The  line  being  formed,  the  major  and  his  staff  take  post, 
facing  the  center  of  the  battalion.  The  adjutant  then  moves 
at  a  trot  or  gallop  by  the  shortest  line  to  a  point  midway  be- 
tween the  major  and  the  center  of  the  battalion,  halts,  facing 
the  major,  salutes  and  reports :  Sir,  the  battalion  is  formed. 

The  major  returns  the  salute. 

The  adjutant  then  takes  his  post  with  the  battalion  staff. 

284.  The  battalion  may  also  be  assembled  in  any  other  con- 
venient  formation.     In   such   cases,   as    soon   as   the   last   com- 
pany   has    taken    its    place    the    adjutant   joins    the    major    and 
reports  to  him  that  the  battalion  is  formed. 

285.  Officers  draw  and  return  saber  with  the  major.    At  cere- 
monies, sabers  are  habitually  drawn ;  at  other  times,  they  are 
drawn  or  kept  in  the  scabbard  at  the  discretion  of  the  major. 

TO    ALIGN    THE    BATTALION 

286.  To  effect  a  general  alignment  the  major  causes  one  of 
the  flank  companies  to  be  established  in  the  desired  position, 
and  commands :  1.  Right  (left),  2.  DRESS. 


THE  FIELD  BATTALION  179 

Each  captain  in  turn,  commencing  with  the  company  first 
posted,  aligns  his  company  toward  the  flank  designated,  and 
commands  front  when  the  alignment  is  complete. 

The  captain  of  the  company  first  established  superintends 
the  alignment  from  the  flank  of  his  company  nearest  the  point 
of  rest.  The  captains  of  the  other  companies  superintend  the 
alignment  from  the  flank  of  their  companies  farthest  from  the 
point  of  rest. 

TO  DISMISS  THE  BATTALION 

287.  The  major  commands:  Dismiss  your  companies,  or  sends 
appropriate  instructions  to  the  captains.    Each  captain  marches 
his  company  to  its  park  and  dismisses  it. 

MANEUVERS    OF    THE    BATTALION 

288.  Formal  maneuvers  of  the  battalion  are  of  limited  appli- 
cation. 

For  passing  from  one  formation  to  another,  and  for  the 
simple  evolutions  requisite  for  ceremonies  and  the  ordinary 
incidents  of  service,  the  battalion  is  maneuvered  in  accordance 
with  the  principles  heretofore  prescribed  for  the  separate  com- 
panies and  by  similar  commands.  In  the  case  of  simultaneous 
movements,  such  as  marching  to  the  front,  to  the  flank,  to  the 
rear,  or  obliquely,  the  command  or  signal  of  execution  of  the 
major  is  immediately  repeated  by  the  captains  and  simultane- 
ously executed  by  the  companies.  In  the  case  of  successive 
movements,  the  captains  maneuver  their  companies  so  as  to 
cause  them  to  assume  their  proper  positions  by  the  shortest 
route  and  in  conformity  with  the  principles  of  the  rules  of 
gaits. 

289.  The  commands  of  the  major  are  transmitted  by  order- 
lies or  given  by  arm,  saber,  or  trumpet  signals,  or  by  word  of 
mouth.     The  captains  habitually  repeat  the  commands   of  the 
major,  or  give  such  commands  as  may  be  necessary  to  insure 
the  execution  of  the  movement.      Their   commands    are    given 
by  arm  or  saber  signal,  or  by  word  of  mouth.     The  whistle, 
and  not   the   trumpet,   is   habitually   used   to   attract    attention 
to    the    signals    of    the    captain    during   the    evolutions    of    the 
battalion. 

EMPLOYMENT    OF   THE    BATTALION 

290.  The  field  battalion  is  a  technical  and  an  administrative 
unit.    The  headquarters  and  supply  detachment  concerns  itself 
principally  with  matters  of  administration  and  supply. 


180  MILITARY  SIGNAL  C'OKI'S  MANUAL 

291.  The  tactical  function  of  the  battalion  is  limited  to  the 
sum  of  the  functions  of  the  three  separate  companies  in  the 
battalion,  as  the  companies  have,  in  general,  separate  spheres 
of  action. 

292.  The  major  will,  however,  direct  and  supervise  the  train- 
ing and  instruction  of  the  companies  in  camp  and  garrison  and, 
will,  in   the   field,  direct,   supervise,  and   co-ordinate   the   v/ork 
of  the  companies   in   the  battalion   in   a  manner   calculated  to 
furnish   the  most  efficient   service   of   information   possible   for 
the  division.     Under  his   direction   members   of   each   company 
will  be  instructed  and  trained  in  the   duties  pertaining  to  in- 
dividuals in  the  other  companies  of  the  battalion. 

293.  It  is  probable  that  the  major  commanding  a  field  bat- 
talion will  often  serve  on  the  staff  of  the  division  commander 
as  division   signal  officer.     When  such   a   situation  obtains,  he 
will  consider  himself  the  technical  adviser  of  the  division  com- 
mander and  of  the  chief  of  staff  in  all  matters  pertaining  to 
signal  corps  work.     He   should  enjoy  the  complete  confidence 
of  his  commander.     He  will  make  timely  recommendations  as 
to  the  employment  of  the  units  in  the  battalion  and  will  take 
appropriate    steps   to    acquaint   the    above-named    officers   with 
the  technical  and  tactical  possibilities  and  limitations  of  field 
signal  troops  as  situations  arise.    When  a  number  of  the  divi- 
sion staff,  he  keeps  himself  informed  as  to  the  state  of  supply 
of    articles    of    signal    corps    equipment    in    the    hands    of    line 
troops  and  arranges  for  the  replacement  of  these  articles  from 
the  supply  depots  in  rear. 


TELEGRAPH  SIGNAL  TROOPS 

FUNCTION  AND  EMPLOYMENT 

Lines  of  information  may  be  either  strategical  or  tactical. 

Strategical  lines  of  information  extend  from  the  seat  of 
government  to  the  several  divisional  headquarters  in  the  held. 
All  lines  of  information  connecting  the  division  headquarters 
with  any  of  its  component  parts  are  tactical.  Tactical  lines  of 
information  are  handled  by  field  signal  troops ;  strategical 
lines  by  base  line  or  telegraph  signal  troops,  according  to 
circumstances. 

Strategical  lines  of  information  are  divided  into  two  zones. 

The  base  line  or  inner  strategical  zone  comprises  that  por- 
tion of  the  strategical  lines  of  information  included  between 
the  seat  of  government  and  advance  base  or  bases  of  armies 
in  the  field.  Information  duties  pertaining  to  this  zone  are 
handled  by  base  line  signal  troops. 

The  telegraph  or  outer  strategical  zone  embraces  that  por- 
tion of  the  strategical  lines  of  information  included  between 
the  advance  base  or  bases  of  armies  in  the  field  and  the  several 
divisional  headquarters.  Information  duties  pertaining  to  this 
zone  are  handled  by  telegraph  signal  troops.  In  addition,  these 
troops  are  designed  to  furnish  certain  administrative  lines  of 
information  in  the  shape  of  camp  telephone  systems  for  the 
larger  units  in  the  field  whenever  circumstances  render  the 
same  necessary  or  advisable. 

The  duties  of  telegraph  signal  troops,  although  only  equipped 
to  install  and  operate  semi-permanent  telegraph  and  telephone 
lines,  include  the  handling  of  every  class  of  communication 
within  their  prescribed  zone.  Whenever  the  installation  or 
operation  of  radio  or  cable  systems  or  any  other  form  of  com- 
munication becomes  necessary  within  the  telegraph  zone  neces- 
sary additions  to  the  personnel  and  materiel  of  the  troops 
will  be  made  to  accomplish  the  purpose  in  hand. 

181 


182  MILITARY  S1GXAL  CORPS  MANUAL 

On  advance  the  telegraph  zone,  or  a  portion  of  k,  will  gen- 
erally become  merged  into  the  base  line  zone.  In  this  case 
an  adjustment  of  the  duties  of  base  line  and  telegraph  signal 
troops  will  be  necessary.  Provision  should,  if  practicable,  be 
made  for  this  beforehand,  and  the  working  of  these  classes  of 
troops,  each  within  its  proper  zone,  now  included  between  new 
points  on  the  terrain,  should  be  established  as  rapidly  and 
with  as  little  confusion  as  possible. 

On  retirement  reverse  conditions  to  advance  will  generally 
obtain.  A  portion  of  the  base  line  zone  (a  new  telegraph 
zone)  will  be  surrendered  by  the  base  line  to  the  telegraph 
troops  for  operation  and  maintenance. 

Cases  will,  no  doubt,  frequently  arise  where  base  line  and 
telegraph  troops  will  be  compelled  to  operate,  for  a  time  at 
least,  in  a  zone  to  which  they  are  not  normally  assigned.  As 
soon  as  practicable,  however,  changes  should  be  effected  to 
circumscribe  their  activities  within  the  properly  denned 
boundaries. 

Telegraph  signal  troops,  although  construction  units,  are 
designed  to  be  mobile.  For  this  reason  only  a  limited  amount 
of  construction  and  operation  material  is  supplied  as  iheir 
equipment.  Their  capability  for  construction  work  is,  how- 
ever, unlimited,  provided  the  requisite  material  be  furnished. 
Installations  of  this  kind  can  usually  be  anticipated  and  pre- 
paration should  be  made  beforehand,  whenever  practicable, 
to  supply  whatever  is  needed  at  points  convenient  for  use. 

Telegraph  signal  troops  are  organized  into  battalions  for 
proper  administration,  supervision,  and  control.  One  or  more 
telegraph  battalions  is  assigned  as  a  component  part  of  army 
corps  troops.  These  are  directly  under  the  corps  commander, 
who  assigns  them  such  duties  within  iheir  province  as  neces- 
sity demands, 


THE   TELEGRAPH   COMPANY 

GENERAL  PROVISIONS 


294.  The  telegraph  company  is  the  principal  signal  adminis- 
trative unit  in  the  telegraph  zone. 

Its  employment  will  be  in  accordance  with  the  needs  of  the 
situation  and  may  be  either  the  working  of  sections  or  pla- 
toons or  the  entire  company  at  isolated  or  on  contiguous  sec- 
tions of  line  as  may  be  necessary.  Whenever  practicable,  a 
dispersed  company  should  be  reassembled,  if  only  for  a  short 
period  of  time,  as  in  this  way  company  administration  is  facili- 
tated and  organization  as  a  whole  kept  intact. 


ORGANIZATION" 

295.  The   telegraph    company   is   organized   into   a   company 
headquarters  and  two  platoons  of  two  sections  each.    Two  of 
the  four  sections  of  the  company  are  telegraph,  and  two  tele- 
phone sections.     A  platoon,  commanded  by  a  first  lieutenant, 
may  consist  of  two  telegraph  or  two  telephone  sections,  or  it 
may  consist  of  one  telegraph  and  one  telephone  section  as  cir- 
cumstances  may  warrant. 

For  the  purpose  of  enhancing  their  mobility,  telegraph  com- 
panies are  equipped  with  motor  transportation.  Trje  sections, 
both  telegraph  and  telephone,  are  organized  as  nearly  alike  as 
possible  as  to  transportation,  materiel,  and  personnel,  so  as  to 
allow  an  interchange  of  duties  if  desirable. 

296.  The  organization,  in  detail,  is  as  follows: 

183 


184 


MILITARY  SIGNAL  CORPS  MANUAL 


1  captain. 

2  first    lieutenants. 

2  master  signal  electricians. 
1  first  sergeant  (sergeant,  first 

class). 

1  supply  sergeant  (sergeant). 
1  mess  sergeant  (sergeant). 
5  mechanics     (1     sergeant,     4 

corporals). 
J  clerk  (corporal). 

1  horseshoer   (as   blacksmith). 

2  cooks. 

2  buglers  (as  messengers,  pri- 
vates,  first   class). 


2  motorcycle  drivers  (for  pla- 
toon chiefs,  privates,  first 
class). 

1  driver  (for  captain's  inspec- 
tion car,  privates,  first 
class). 

1  driver,   truck    (private,    first 

class). 

2  telegraph    sections    (22   men 

each). 

2  telephone  sections  (18  men- 
each. 


DUTIES    OF    INDIVIDUALS 

297.  In  the  telegraph  company  the  duties  of  the  captain, 
lieutenants,  master  signal  electricians,  first  sergeant,  supply 
sergeant,  mess  sergeant,  chiefs  of  section,  operators,  and  mes- 
sengers assimilate  those  prescribed  for  like  grades  in  field 
companies  as  far  as  applicable. 

The  chief  mechanic  is  assigned  to  general  charge  of  motor 
transportation  and  is  responsible  to  the  captain  for  its  efficient 
working  at  all  times.  In  addition,  he  supervises  repair  work 
to  all  other  material  belonging  to  the  company.  In  these 
duties  he  is  assisted  by  the  other  mechanics. 

The  horseshoer  is  assigned  to  duty  under  the  chief  mechanic. 

The  drivers  are  responsible  for  the  efficient  working  order 
of  motor  vehicles  under  their  charge  and  for  their  care  and 
adjustment.  They  are  also  responsible  for  the  proper  hand- 
ling of  vehicles  on  the  road. 

THE  TELEGRAPH  SECTION 


COMPOSITION 

298.  The  section,  whether  telegraph  or  telephone,  is  the 
working  unit.  All  duties  performed  by  platoons,  companies,  or 
battalions  of  telegraph  signal  troops  consist  of  but  the  com- 
bined work  of  a  number  of  sections.  Units  larger  than  the 
section  are  necessary  only  for  efficient  administration,  sup- 
ervision, and  control. 

The  telegraph  section  consists  of  22  men. 

Its  organization,  in  detail,  is  as  follows: 
1  chief  of  section  (sergeant,  first  class). 
1  chief  operator  (sergeant,  first  class). 


THE  TELEGRAPH  COMPANY  185 

1  chief  lineman  (sergeant). 

6  operators  (1  sergeant,  2  corporals,  and  3  privates,  first 

class). 

8  linemen  (1  corporal,  6  privates,  first  class,  1  private). 
3  drivers  (privates,  first  class). 

2  messengers  (privates). 

Total,  22. 


ORGANIZATION    AND    EQUIPMENT 

299.  The  section  is  organized  and  equipped  to  install,  operate, 
and  maintain  20  miles  of  semi-permanent  telegraph  line.  Undei 
ordinary  conditions  this  installation  should  take  place  within 
one  working  day. 

The  transportation  furnished  permits  from  four  to  six  men  to 
ride  upon  motorcycles  or  side  cars.  The  remaining  men,  with 
all  personal  baggage,  and  the  prescribed  section  technical  will 
be  carried  upon  the  section  trucks. 

After  all  material  carried  by  the  section  has  been  installed, 
it  may  be  called  upon  to  build  other  sections  of  line  or  it  may 
be  called  upon  to  operate  the  section  or  sections  already  in 
position.  In  the  former  case,  additional  material  for  daily 
construction  work  must  be  supplied  by  other  transportation. 
In  case  of  the  operation  and  maintenance  of  a  section  of  line, 
the  personnel  of  the  section  will  be  distributed  over  the  line 
in  such  a  manner  as  will  best  facilitate  this  work.  The  sec- 
tion is  expected  to  be  a  self-sustaining  unit  under  any  and  all 
conditions. 


DUTIES   OF   INDIVIDUALS 

300.  The  chief  of  section  exercises  general  supervision  of 
his  section  at  all  times. 

The  chief  operator  exercises  the  function  indicated  by  his 
title  when  the  section  is  operating  a  section  of  line.  At  other 
times  he  performs  such  special  duties  as  may  be  assigned  to 
him  by  the  chief  of  section. 

The  chief  lineman  supervises  construction  or  maintenance 
work  according  as  the  section  is  installing  or  operating  line. 

The  operators  (two  for  each  station)  operate  their  stations 
when  installed.  During  installation  they  perform  such  line 
work  as  may  be  assigned  to  them  by  the  chief  of  section. 

The  linemen  install  or  maintain  the  line  as  may  be  necessary 
under  the  direction  of  the  chief  lineman. 

The  drivers  operate  their  trucks  as  may  be  necessary  in 
installation  and  maintenance. 


186 


MILITARY  SIGNAL  CORt'S  MAM'AL 


The  messengers  are  assigned  to  duty  transporting  men  or 
material  in  the  motorcycles  or  side  cars  as  they  may  be  directed 
by  the  chief  of  section  during  both  installation  and  mainten- 


XUMERICAL   DESIGNATION    OF    MEMBERS 

301.  The  men  of  the  telegraph  section,  except  the  chief  of 
section,  chief  operator,  and  chief  lineman  are  numbered  from 
1  to  19  for  the  purpose  of  prescribing  their  positions  amd 
duties  in  various  drills  and  formations. 

Specifically,  they  are  numbered  as  follows : 


1.  Sergeant,  operator. 

2.  Corporal,  operator. 

3.  Corporal,  operator. 

4.  Private,  first  class,  operator. 

5.  Private,  first   class,  operator. 

6.  Private,  first  class,  operator. 


^Operating  squad. 


7.  Corporal,  lineman. 

8.  Private,  first    class  lineman. 

9.  Private,  first    class,  lineman. 

10.  Private,  first    class,  lineman. 

11.  Private,  first    class,  lineman. 

12.  Private,  first    class,  lineman. 

13.  Private,  first    class,  lineman. 

14.  Private,  lineman. 

15.  Private,  messenger. 

16.  Private,  messenger. 

17.  Private,  first   class,  driver. 

18.  Private,  first    class,  driver. 

19.  Private,  first    class,  driver. 


J^Line  squad. 


(.Messenger  squad. 


; 


Driving  squad. 


C.  S. — Chief  of  section. 
C.  O. — Chief  operator. 
C.  L. — Chief  lineman. 

302.  The  above  division  into  squads  has  for  its  purpose  only 
the  general  grouping  of  individuals  commonly  expected  to  per- 
form similar  duties.  In  forming  the  section  the  individuals 


T111L   TILLING  RAT  1 1  COM  I' AS  Y 


187 


FORMATION  OF  THE 
TELEGRAPH  SECTION 


FORMATION  OF  THE 
TELEPHONE  SECTION 

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TELEGRAPH  SECTION 
IN  COLUMN 


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C.S.  '    CHttF  OF  SECTION 
C.O  •    CHIEF  OPERATOR 
C.L       CHIEF  LINEMAN 


TELEGRAPH  SECTION 
:  TRUCK  W  1  -  LANCE  TRUCK 
1  TRUCK  in  •  LANCE  TRUCK 
TIUCK  Wi-  WIRE  TRUCK 


TELEPHONE  SECTION 
TKUCK  \fti  -  SW60  TRUCK 
TRUCK  M-   WIRE  TRUCK 
TRUCK  *}-.  LANCE  TRUO 


THE   TELEGRAPH    COMPANY   AND   ITS    SUBDIVISIONS 


188  MILITARY  SIGNAL  CORPS  MANUAL 

are  so  arranged  as  to  preserve  the  integrity  of  the  squads.  In 
the  performance  of  technical  work  the  men  are  assigned  to 
duty  without  reference  to  original  grouping  whenever  rapidity 
and  efficiency  can  be  gained  thereby. 


FORMATION  OF  THE  SECTION 

303.  The   section  is  formed  in  line  in  double  rank  with  the 
odd  numbers  in  the  rear  rank  and  even  numbers  in  the  front 
rank.    The  chief  of  section  is  2  yards  in  front  and  center  of  his 
section,  the  messengers  and  drivers  in  the  line  of  the  file  closers. 

POSTS     OF     INDIVIDUALS 

304.  Positions  of  all  individuals  are  as  shown  in  accompany- 
ing drawing. 

DISTRIBUTION    OF     MATERIEL    FOR    TRANSPORT 

305.  The  assignment  of  materiel  to  the  several  carriages  for 
transport  is  such  that  each  carriage,  with  its  assigned  person- 
nel, will  have  approximately  its  maximum  load.     The  distribu- 
tion of  personnel  and  materiel  is  also  planned  so  as  to  have 
these   readily  available   for   construction   work. 

Specifically,  the  section  carriages  are  loaded  as  follows : 

Truck  No.  1 :  One  half  the  lance  poles  of  the  section  (300), 
with  insulators  for  same. 

Truck  No.  2:  Same  as  truck  No.  1,  except  add  digging  bars 
and  tamping  bars. 

Truck  No.  3:  All  wire,  tools,  station  equipment,  and  other 
miscellaneous  materiel  belonging  to  the  section. 

The  above  distribution  of  materiel  is  considered  normal.  It 
can  and  should  be  varied  if  good  reasons  for  this  procedure  arc 
apparent. 

TO  FORM   THE   SECTION 

306.  The  section  falls  in  as  a  dismounted  double  rank  at  the 
order  of  its   chief,  who  posts   himself   facing  it  2  yards   from 
where  the  center  is  to  rest.     The   chief  of  section   then   calls 
the  roll  or  otherwise  verifies   the  personnel,  and  directs   it  to 
call  off.    He  then  directs  the  file  closers  to  fall  out  and  marches 
the   remainder    of   the    section    to   the    storerooms,   where    the 
trucks    are   brought    up   by   their    drivers.     He    then    gives    the 
command:  PACK  OUT.     The  personnel  assigned  to  each  truck 
then  proceeds  to  load  the  truck,  each  with  its  proper  technical 


THE  TELEGRAPH  COMPANY  189 

materiel,  under  supervision  of  the  ranking  noncommissioned 
officer  present  with  it. 

Ordinarily  the  corporal  lineman  (No.  7)  supervises  the  load- 
ing of  truck  No.  1;  the  chief  operator,  of  truck  No.  2;  and  the 
sergeant  operator  (No.  1),  of  truck  No.  3. 

The  trucks  being  loaded,  all  carriages  are  again  formed  in 
park,  the  personnel  forming  in  line  2  yards  in  front  of  the 
center  of  the  carriages. 

The  chief  of  section  then  makes  a  minute  inspection  of  the 
equipment,  carriages,  and  personnel  and  gives  such  orders  or 
directions  as  may  be  necessary. 


SECTION'    MANEUVER 

To  Mount  and  Dismount 

307.  The  section  being  dismounted  in  line,  the  carriages  in 
any  formation,  the  chief  of  section  commands :  MOUNT  UP. 

At  this  command  each  driver  and  messenger  mounts  his 
carriage  and,  unless  otherwise  directed,  starts  his  motor. 

The  personnel  assigned  to  the  various  carriages  for  trans- 
port proceed  to  them  by  the  shortest  practicable  route  and 
mount. 

308.  Being  in  line  at  a  halt  to  dismount  the  section,  the  chief 
of  section  dismounts  from  his  carriage  and  commands:   DIS- 
MOUNT. 

At  this  command  the  drivers  stop  their  motors,  if  running, 
and  all  personnel  dismount  and  form  in  line  2  yards  in  front 
of  the  center  carriage. 

The  section  at  a  halt  in  any  formation  may  be  dismounted 
according  to  the  same  principles.  In  this  case  the  chief  of  sec- 
tion designates  the  position  where  the  section  dismounted  is  to 
form  in  line. 

To  Leave  the  Park 

309.  The  chief  of  section   signals  forward  and  moves  out  in 
his  own  carriage.     The  remaining  carriages  follow  in  the  pre- 
scribed order  of  route. 

To  Conduct  the  Section  En  Route 

310.  The  section  marches  in  the  order  prescribed. 

All  drivers  observe  strictly  the  rules  of  the  road.  Except 
in  emergency,  the  gait  should  not  exceed  12  miles  per  hour. 


190  MILITARY  SIGNAL  CORPS  MANUAL 

The  prescribed  distance  of  15  yards  between  carriages  is  the 
minimum  safe  distance  at  which  the  carriages  should  follow 
each  other.  Road  conditions  will  frequently  make  a  greater 
distance  necessary  or  desirable;  the  section  should  remain 
closed  to  15  yards  as  far  as  the  prudent  conduct  of  travel 
permits. 

If  the  section  is  to  travel  any  distance  alone,  one  of  the 
motorcycles,  preferably  No.  2,  should  march  in  rear  of  the 
column. 

To  Halt 

311.  The  chief  of  section  signals  HALT  and  stops  his  car- 
riage.    The  other  carriages  halt  at  15  yards  from  the  one  pre- 
ceding.   The  carriages  may  be  directed  to  close  to  shorter  dis- 
tances  if   desired. 

To  Dismiss  the  Section 

312.  The    section    being    in    park    and    the    personnel    being 
mounted  on  the  carriages,  the  chief  of  section  dismounts  and 
commands :  PACK  IN.    At  this  command  the  trucks  proceed  to 
the  storerooms  and  the  materiel  is   unloaded  and  disposed  of 
under  supervision  of  senior  noncommissioned  officer   on   each 
truck,  generally  supervised  by  the  chief  of  section.    The  drivers 
then   return   their   trucks   to   the   park.     The   chief  of   section 
marches   the   section    (less    driving  and   messenger   squads)    to 
the  parade  ground  and  dismisses  it.    The  chief  lineman  inspects 
all    carriages    and    thereafter    dismisses    the    drivers    and    mes- 
sengers. 

TECHNICAL  DRILL 
General   Provisions 

313.  The  lance  pole  telegraph  line  is  classed  as  a  semi-perma- 
nent line.     It  should,  however,  be  erected  as  carefully  and  sub- 
stantially   as    practicable,   with    a    view    to    the    elimination    of 
line  trouble  as  well  as  on  account  of  the  fact  that  it  can  never 
be   foretold  just   how   long  the   line   will   have   to   be   operated 
before    being    superseded    by    permanent    construction 

314.  The    technical    drill,   while    minutely    described    by    the 
exact    assignment    of    duties    to    the    various    members    of    the 
section,  is  necessarily  but  a  general  guide.     The  situation  will 
not  only  vary  greatly  with  establishment  of  every  new  section 
line,  but   construction   will   also  differ  considerably   in   various 
parts  of  any  line.    The  section  or  other  commander  should  not 
hesitate   to   vary   from  the   drill   if   it    appears    advisable. 


THE  TELr.CR.irn  rru/r./.vr  191 

315.  Thoroughly  substantial  construction,  completed  as  rap- 
idly as  possible,  should  be  the  object  sought  in  the  assignment 
of  men,  tools,  and  materiel,  and  any  assignment,  as  applied  to 
the    situation    in    hand,    which    best    accomplishes    this    object 
should   be  the  one  employed. 

To  Prepare  to  Open  Station 

316.  On  arrival  at  the  point  where  construction  is  to  begin 
the  chief  of  section  halts   the   section,  dismounts,  and  directs 
the  carriages  to  close  to  5  yards  distance.    He  then  commands: 
PREPARE  TO  OPEN  STATION. 

At  this  command  all  dismount  except  the  drivers  and  mes- 
sengers, and  each  member  provides  himself  with  the  proper 
tools  or  equipment  incident  to  his  employment  in  line  con- 
struction. The  section  is  then  formed  in  line  by  the  chief 
of  section,  who  verifies  the  men  and  the  individual  equipment 
of  each. 

To  Open  Station 

317.  The  chief  of  section  commands  :  OPEN  STATION. 

At  this  command  the  first  station  is  installed  and  con- 
struction work  is  begun,  the  line  being  erected  generally  as 
follows  :  The  insulators  are  placed  upon  the  poles,  which  are 
dropped  at  points  convenient  for  erecting.  Pigtails  are  placed 
on  all  poles  except  those  intended  to  be  guyed.  In  straight 
stretches  every  fifth  pole  is  guyed  usually  both  ways  against 
the  line.  Poles  to  be  guyed  are  equipped  with  pony  insulators. 
Holes  to  receive  the  poles  are  dug  at  proper  points.  The  wire 
which  has  been  laid  along  the  route  is  inserted  in  the  tail 
of  the  pigtail  and  the  poles  equipped  with  these  insulators  are 
then  erected  and  thoroughly  tamped. 

The  slack  is  pulled  up  at  every  pole  equipped  with  a  pony 
insulator,  the  tie  being  made  on  this  pole  while  on  the  ground 
near  the  hole  dug  to  receive  it.  This  pole  is  then  erected, 
tamped,  and  guyed. 

318.  The  duties  of  each  member  of  the  section  incident  to 
constructing  the  line  are  as  follows  : 

Chief  of  section :  General  supervision  of  construction,  includ- 
ing necessary  reconnaissance.  Utilizes  to  best  advantage  men 
not  specifically  engaged  and  in  general  takes  such  steps  as 
may  be  necessary  to  accomplish  as  rapid  construction  as  is 
consistent  with  stability. 

Chief  operator :  Sees  that  station  property  is  unloaded  at 
various  stations  and  that  same  is  properly  installed.  Assigns 


192  MILITARY  S1GXAL  CORPS  MANUAL 

operators  to  stations  where  necessary.  Inspects  line  after 
erection  of  same  is  complete.  Replaces  broken  poles  or  in- 
sulators where  necessary,  sees  that  all  guys  are  taut  and  in 
general  removes  any  apparent  trouble  from  the  line.  Covers 
the  line  about  one-half  mile  behind  tail  of  construction  party 
in  truck  No.  2. 

Chief  lineman:  With  No.  8  constitutes  first  erecting  squad. 
Pulls  up  slack,  ties  and  guy  poles  at  which  this  procedure  is 
necessary. 

No.  1 :  Remains  at  station  1  to  care  for  station  property 
and  operate  station  if  necessary. 

No.  2:  Operator  station  2.  Rides  from  station  1  to  station  2 
on  truck  No.  3. 

No.  3:  Rides  on  truck  No.  1  and  superintends  unloading  of 
poles.  Sees  that  poles  are  properly  spaced  and  provided  with 
insulators  of  the  proper  kind.  Sees  that  double  or  triple  poles 
are  unloaded  at  road  crossings  and  other  proper  points.  Also 
sees  that  guys  are  dropped  in  sufficient  number  at  points  where 
same  v/ill  be  needed. 

No.  4:  Accompanies  truck  No.  1.  Fits  insulators  on  poles 
and  unloads  same  as  per  directions  of  No.  3. 

No.  5:  Rides  on  truck  No.  3  and  pays  out  wire  from  reel. 
Attends  splices. 

No.  6:  Assists  No.  5  on  truck  No.  3.  Takes  first  trick  as 
operator  at  station  3. 

No.  7:  Assistant  chief  lineman  :  With  No.  9  constitutes  second 
erecting  squad.  Pulls  up  slack,  ties  and  guys  poles  where  this 
procedure  is  necessary. 

No  8:  Duty  with  first  erecting  squad. 

No.  9:  Duty  with  second  erecting  squad. 

No.  10:  Checks  tension  from  a  point  midway  between  ties. 

Nos.  11,  12,  13,  and  14,  Hole  diggers  :  Dig  holes  and  erect  and 
tamp  all  poles  not  tied  in. 

Nos.  15  and  16:  Messengers:  Relay  erecting  squads,  hole 
diggers,  and  No.  10  forward  as  necessary. 

Nos.  17,  18,  and  19:  Operate  the  trucks. 

To  Prepare  to  Close  Station 

319.  Before  recovering  the  line  the  section  transportation 
and  a  large  portion  of  the  personnel  should  be  assembled  at  the 
point  where  recovery  is  to  begin.  This  point  should  normally 
be  at  one  end  of  the  section. 

Preparatory  to  recovering  the  line  the  chief  of  section  com- 
mands :  PREPARE  TO  CLOSE  STATION. 


THE  TELEGRAPH  COMPANY  193 

At  this  command  the  operator  on  duty  at  the  station  sends 
GB  to  all  stations  and  gets  acknowledgment  of  same.  All 
members  of  the  section  procure  necessary  equipment  to  be  used 
in  recovering  the  line  and  form  for  inspection  as  in  prepare  to 
open  station. 

To  Close  Station 

320.  To  commence  recovery  of  the  line  the  chief  of  section 
commands  :  CLOSE  STATION. 

The  line  is  recovered  generally  as  follows:  The  poles  are 
taken  down,  insulators  and  guys  removed  and  loaded  on  the 
designated  truck.  The  wire  is  reeled  up  in  approximately  l/2- 
mile  coils  and  loaded  on  truck  No.  3. 

321.  The  duties  of  each  member  of  the  section  incident  to  the 
recovery  of  the  line  are  as  follows: 

Chief  of   section  :  Same  as   in  constructing  line. 

Chief  operator :  Sees  that  station  property  is  loaded  on  at 
first  and  succeeding  stations.  . 

Chief  lineman:  Assisted  by  No.  8,  removes  every  alternate 
guyed  pole. 

No.  1 :  Operator  at  first  station.  No  duties  except  to  load  and 
pack  station  property  on  truck  No.  3  at  proper  time. 

No.  2 :  Operator  at  second  station.    Duties  same  as  No.  1. 

Nos.  3  and  4:  Assisted  by  No.  11,  load  poles,  guys,  and  in- 
sulators on  truck  No.  1. 

Nos.  5  and  6:  Assisted  by  No.  10,  reel  up  wire  on  truck  No. 
3.  Bind  up  in  J^-mile  coils  and  load  on  truck. 

No.  7:  Assisted  by  No.  9,  removes  every  alternate  guyed 
pole. 

No.  8:  Assists  chief  lineman. 

No.  9:  Assists  No.  7. 

No.  10:   Assists  Nos.  5  and  6. 

No.  11  :  Assists  Nos.  3  and  4. 

Nos.  12,  13,  and  14:  Same  as  duties  Nos.  3,  4,  and  11,  but 
with  truck  No.  2. 

Nos.  15  and  16:  Relay  the  squads  removing  guyed  poles. 

Nos.  17,  18,  and  19:  Operate  trucks  incident  to  recovery  of 
line. 

322.  The  technical  drill  of  the  section  is  not  expected  neces- 
sarily to  cover  the  normal  or  usual  case  in  either  construction 
or  recovery.    It  is  prescribed  as  a  drill  wholly  for  the  purpose 
of  training  the  section  members  in  their  various  duties  and  for 
the  conduct  of  the  work  by  squads  in  an  orderly  and  methodical 
manner. 

In  construction  work  where  the  line  is  erected  on  supports 
other  than  lance  poles,  the  chief  of  section  makes  such  changes 


194  MILITARY  S1C,\.\J.  CORPS  M.lXl'.lL 

in    assignments    of    duty    of    the    various    section    members    as 
will  best  facilitate  the  work  in   hand. 

The  drill  for  closing  station  assumes  that  the  entire  section 
(less  2  operators)  is  assembled  at  one  end  of  the  line.  If  such 
is  not  the  case  (and  this  condition  is  usually  to  be  expected), 
the  chief  of  section  gives  suitable  directions  and  makes  such 
assignments  as  are  necessary  to  recover  the  line  prior  to 
assembly,  if  practicable. 

To  Work  with  Reduced  Numbers 

323.  The  erection  of  a  semi-permanent  telegraph  line  may  be 
readily  effected  by  a  much  smaller  team  than  the  regular  tele- 
graph section  if  time  of  construction  is  not  a  dominant  factor. 
In  fact,  the  telegraph  section  is  designed  as  the  maximum  crew 
which  can  be  profitably  engaged  in  work  at  a  single  point  and 
at  the  same  time  operate  each  station  as  soon  as  installed. 

The  following  is  a  guide  for  the  employment  of  individuals 
when  the  section  is  reduced"  below  the  quota  authorized  in  the 
organization  table : 


CONSTRUCTION 

324.  With  21  men. — Omit  No.  2.  Second  station  not  to  be 
cut  in  until  line  is  completed. 

With  SO  men. — Omit  Nos.  1  and  2.  No  station  to  be  established 
until  line  is  completed.  Directions  for  use  of  21  or  20  men 
assumes  operation  of  stations  during  the  construction  period  is 
not  imperative.  If,  however,  the  operation  of  one  or  more  stations 
are  necessary,  variations  will  have  to  be  made  in  the  assignment 
of  duties  of  section  members  to  permit  provision  for  the  neces- 
sary number  of  operators. 

With  19  -men. — Omit  No.  6.     No.  5  operates  wire  truck  alone. 

With  18  men. — Omit  No.  11.  This  leaves  one  digging  bar  not 
in  use  for  the  time  being.  It  is  carried  on  the  wire  truck  and 
used  by  either  erecting  squad  to  dig  holes  for  poles  tied  in  if 
diggers  get  behind  in  their  work. 

With  1~  men.— Omit  No.  4.    No.  3  handles  the  poles  alone. 

With  16  men.—Omh  No.  15.  Chief  of  section  takes  motor- 
cycle and  performs  this  duty  as  necessary. 

With  15  men. — Omit  No.  10.  Chief  of  section  checks  tension 
in  addition  to  other  duties. 

With  14  men.— Omit  No.  12.  This  leaves  but  two  hole  diggers 
and  two  unused  bars.  One  bar  is  taken  by  each  erecting  squad 
who  digs  all  holes  for  poles  tied  in. 


THE  TELEGRAPH  COMPANY  195 

With  13  men. — Second  erecting  squad  disbande'd.  Omit  No.  9. 
Chief  lineman,  Nos.  7  and  8  constitute  only  erecting  squad  and 
dig  holes  for  tied-in  poles. 

With  1^  men.— Omit  No.  8. 

With   11    men. — Omit    No.    7.     Chief   operator   takes    his    place. 

With  10  men. — Omit  chief  lineman.  Chief  of  section  acts  as 
chief  lineman.  No.  16  checks  tension  in  addition  to  his  other 
duties. 

With  9  men.— Omit  No.  13. 

With  8  men. — Omit  No.  3  No.  17  frames  and  drops  poles  in 
addition  to  driving  truck. 

With  ~  men. — Omit  No.  16.  Chief  operator  takes  motorcycle 
and  performs  necessary  duty  therewith. 

With  6  to  8  men. — No  specific  duties  can  be  prescribed.  With 
such  a  small  number  of  men  the  various  operations  in  connection 
with  construction  must  be  performed  in  rotation  by  the  same 
men.  It  is  assumed  that  three  men  is  the  smallest  number  who 
can  erect  the  line. 

RECOVERY 

325.  With  21  men. — No  change.  No.  1  has  no  duties. 

With  20  men. — No  change.    No.  2  has  no  duties. 

With  19  men.— Omit  No.  3. 

With  18  men.— Omit  No.  12. 

With  17  men.— Omit  No.  10. 

With  16  men. — Omit  No.  8.  No.  15  performs  No.  8's  duties  in 
addition  to  his  own. 

With  15  men. — Omit  No.  15.  Chief  operator  takes  over  duties 
and  motorcycle. 

With  14  men. — Omit  Xo.  9.  Chief  lineman,  chief  operator, 
and  No.  7  take  down  guyed  poles. 

U'ith  13  men.— Omit  No.  7. 

With  12  men.— Omit  No.  11. 

U'ith  11  men.— Omit  No.  13. 

U'ith  1"  men. — Omit  No.  4.     No.  17  loads  truck  No.  1. 

With  '>  men.— Omit  No.  14.     No.  18  loads  truck  No.  2. 

U'ith  8  men. — Omit  chief  lineman.  Chief  of  seciton  performs 
his  duties. 

With  7  men. — Omit  No.  16.     Chief  of  section  takes  motorcycle. 

With  6  to  3  men. — No  specific  duties  prescribed.  Operations 
of  recovery  must  be  performed  more  or  less  in  rotation. 

LINE    CONSTRUCTION 

Iii  the  construction  of  semi-permanent  telegraph  lines  the 
following  directions  should  be  carefully  observed. 


196  MILITARY  SIGNAL  COKl'S  MANUAL 

Reconnaissance 

If  a  preliminary  reconnaissance  of  the  route  to  be  fol- 
lowed can  be  made  by  the  chief  of  section  or  chief  lineman, 
much  will  be  gained  in  the  matter  of  rapidity  and  stability  of 
installation.  This  will  be  usually  impracticable,  however,  as 
the  immediate  commencement  of  work  will  be  necessary  at  the 
arrival  of  the  section  on  the  ground.  Reconnaissance  should 
be  had  along  the  route  coincident  with,  or  slightly  preceding 
the  construction  proper.  This  can  usually  be  done  by  the 
chief  of  section,  who  should  keep  the  working  parties  in  rear 
constantly  informed  of  any  unusual  conditions  affecting  line 
construction  which  obtain. 

Use  of  Lance  Poles 

These  should  never  be  used  if  any  firmer  I'ne  supports  are 
available.  The  section  carries  only  25  iron  and  no  oak  brack- 
ets. An  ample  number  of  the  latter  fitted  with  insulators 
should  be  especially  supplied  to  any  section  about  to  erect  a 
line  where  it  is  known  good  use  can  be  made  of  them.  Attempt 
should  be  made  to  secure  a  sufficient  number  of  these  locally, 
and  every  effort  possible  made  to  hang  the  line  on  the  strongest 
supports  found  along  the  route. 

To  Take  up  the  Slack 

Slack  is  pulled  up  wherever  a  pole  is  tied  in.  To  do  this 
properly  the  pole  to  be  tied  should  be  laid  upon  the  ground 
about  1  foot  short  of  the  hole.  The  slack  is  then  pulled 
up  from  the  last  tied  pole  by  one  man  4  or  5  yards  forward  of 
the  pole  about  to  be  tied.  The  tension  is  checked  by  a  man 
standing  for  the  purpose  about  midway  between  the  two  ties. 
When  correct  a  signal  is  made  to  this  effect  and  a  round  turn 
is  made  with  the  line  about  the  insulator  before  attaching  the 
tie  wire.  If  this  process  is  properly  carried  out  the  tie  pole 
should  be  exactly  erect  and  with  proper  tension  on  the  line 
between  the  ties. 

Guying  and  Guy  Stakes 

In  straight  stretches  every  fifth  pole  is  usually  guyed  against 
the  line.  A  guyed  pole  infers  that  it  is  also  tied  in.  If  the  line 
is  liable  to  remain  up. sometime  or  stormy  weather  is  anticipated, 
much  greater  line  strength  may  be  obtained  by  guying  four 
ways  on  straights.  All  corners  should  be  guyed  and  care 


THE  TELEGRAPH  COMPANY  197 

should  be  taken  to  see  that  the  guy  is  securely  fastened  both 
to  the  pole  and  the  stake. 

No  special  guy  stakes  are  furnished.  Every  possible  means 
to  fasten  guys  to  stable  supports  along  the  line  should  be 
utilized.  Failing  in  this,  guy  stakes  should  be  improvised  from 
material  found  along  the  route.  In  some  cases  it  may  be  neces- 
sary to  cut  up  lance  poles  to  make  guy  stakes.  This  procedure 
should  be  limited  to  broken  poles  as  far  as  possible,  the  same 
being  preserved  for  this  purpose. 

To  Cut  in  Stations 

This  is  always  done  in  series,  a  convenient  way  being  to  use 
a  strain  insulator  or  porcelain  knob  as  a  circuit  breaker.  The 
station  is  then  connected  by  cutting  to  ground  or  looping,  de- 
pending on  whether  or  not  the  instrument  is  an  end  or  an  in- 
termediate station. 

Digging  Methods 

To  start  the  diggers  promptly  and  to  provide  a  method  for 
readily  getting  them  out  of  the  way  of  the  construction  proper 
the  following  is  suggested.  No.  11  starts  digging  the  first  hole, 
No.  12  goes  to  location  of  second  hole  and  after  being  lined  in 
by  the  chief  lineman  digs  that  hole.  Nos.  13  and  14  are  carried 
forward  by  motorcycle  to  fourth  and  sixth  holes,  respectively. 
Each  hole  digger  then  lines  in  on  the  general  line  by  back  sight 
and  digs  holes.  Every  hole  digger  is  relayed  forward  after  dig- 
ging two  holes.  Generally  two  diggers  are  ready  at  the  same 
time  to  be  carried  forward. 

OPERATION    AND    MAINTENANCE 

The  section  is  furnished  with  sufficient  personnel  to  operate 
three  stations  on  the  section  line  if  the  same  is  desired.  On 
account  of  limited  transportation,  only  a  sufficient  supply  of 
stationery  and  office  material  is  carried  to  permit  the  operation 
of  the  stations  for  a  very  short  time.  If  the  operation  of  the 
stations  for  more  than  two  or  three  days  can  be  anticipated, 
timely  requisition  should  be  made  for  the  necessary  telegraph 
office  material  to  properly  equip  the  stations.  The  continued 
use  of  message  books  and  field  message  envelopes  is  not  satis- 
factory on  semi-permanent  lines.  If  the  stations  are  expected  to 
operate  any  great  length  of  time  a  typewriter  should  be  fur- 
nished to  each 

If  the  line  is  to  be  operated  for  any  extended  period  the 
personnel  and  transportation  should  be  distributed  amongst 


198  MILITARY  SIGNAL  CORPS  MANUAL 

the  various  stations.  No  precise  rule  can  be  laid  down  govern- 
ing this  distribution,  as  it  will  vary  in  different  cases,  but  it 
should  in  general  accord  with  the  following  principles. 

Sufficient  personnel  should  be  attached  to  each  station  to 
permit  the  greatest  ease  of  operation  and  maintenance.  The 
transportation  should  be  distributed  so  that  at  least  one 
motor  vehicle  should  be  at  each  station,  for  the  purpose  of 
covering  the  line  when  necessary.  To  insure  proper  supervision, 
the  chief  of  section,  chief  operator,  and  chief  lineman  should 
each  be  at  separate  stations.  The  quota  of  the  telegraph  sec- 
tion is  based  upon  economy  and  rapidity  in  construction  work; 
the  section  line  can  be  efficiently  operated  and  maintained  by 
a  far  less  number  of  men. 

Lance  line  in  general  is  hard  to  maintain.  In  some  cases 
initial  rugged  construction  will  partially  obviate  this.  The 
presence  of  motor  transportation  makes  the  covering  of  the 
line  a  rapid  and  an  easy  matter.  Under  these  circumstances 
the  entire  line  should  be  covered  daily,  weather  permitting, 
and  such  minute  inspection  made  to  locate  defects  as  will  in 
great  measure  prevent  the  occurrence  of  trouble.  When  trouble 
does  occur  immediate  action,  irrespective  of  time  or  weather, 
should  be  had  to  remove  it. 


THE  TELEPHONE  SECTION 
FUNCTION 

326.  The  primary  function  of  the  telephone  section  is  the 
erection  of  divisional  telephone  systems  at  points  where  the 
permanence  of  the  camp  makes  this  procedure  necessary  or 
desirable.  Furthermore,  the  telephone  section  is  designed  to 
assist  or  substitute  for  telegraph  sections  in  the  construction 
of  semi-permanent  telegraph  lines,  if  conditions  render  the 
performance  of  such  duty  advisable. 


COMPOSITION 

327.  The  telephone  section  consists  of  18  men.     In  detail  it 
is  as  follows : 

1  chief  of  section,  sergeant,  first  class. 
1  chief  operator,  sergeant. 

1  chief  lineman,  sergeant. 

3  switchboard   operators,  corporals. 

7  linemen — 6  privates,  first  class,  1  private. 

3  drivers,  privates,  first  class. 

2  messengers,  privates. 


THE  TELEGRAPH  COMPANY  199 


ORGANIZATION"    AND    EQUIPMENT 

328.  The  section  organized  and  equipped  to  install,  operate, 
maintain  and  recover  one  divisional  semi-permanent  telephone 
system.     The  installation  includes   17  miles  of  metallic  circuit 
(twisted  pair)   line,  one  switchboard,  and  20  camp  telephones. 
The  board  is  wired  to  receive  two  common  battery  trunks  for 
long-distance   work.     No   other   special   additions    or   arrange- 
ments are  necessary  for  this  purpose.    The  installation  will  or- 
dinarily consume  the  greater  part  of  two  working  days. 

329.  The   transportation   is   identical  with   that   of  the   tele- 
graph section,  and  the  materiel  has  many  articles  in  common. 
The  personnel  is  transported  as  in  the  telegraph  section. 

330.  Depending  on  conditions,  the  personnel  of  the  section 
may  be  assigned  to  various  duties  after  its  materiel  is  installed. 
It   may   remain   intact   at   the   station   where   its    equipment  is 
installed,  operating  and  maintaining  the   system  and  being  in 
constant   readiness    to   recover   the   latter   and   transport   it   to 
another  theater  of  operations.     It   may  on  completion  of  the 
installation   be    called   upon   to    proceed   to   other   work,   leav- 
ing the  erected  system  intact  and  sufficient  crew  to  properly 
operate  and   maintain   it.     As   with  the  telegraph  section,  the 
section  is  expected  to  be  a  salf-sustaining  unit  under  all  con- 
ditions. 

DUTIES    OF    INDIVIDUALS 

331.  The  chief  of  section  exercises  general  supervision  over 
the  work  of  his  section. 

The  chief  operator  during  installation  supervises  the  setting 
up  of  the  switchboard  and  the  connection  of  the  various  tele- 
phones. During  operation  he  supervises  the  general  working 
of  the  system  especially  with  reference  to  the  switchboard. 
If  the  system  is  immobilized  and  but  one  man  is  left  with  it, 
the  chief  operator  usually  is  assigned  to  this  duty. 

The  chief  lineman  in  general  supervises  the  construction, 
maintenance,  or  recovery  of  the  line.  In  installation  he  is  espe- 
cially charged  with  the  proper  location  of  the  several  lines. 

The  switchboard  operators  take  active  part  in  installation 
and  recovery  of  lines  performing  such  duties  as  may  be  specifi- 
cally assigned;  during  operation  their  duties  pertain  to  the 
handling  of  the  switchboard. 

The  linemen  install,  maintain,  or  recover  the  lines  under  di- 
rection of  the  chief  lineman  or  chief  of  section. 

The  drivers  operate  their  trucks  as  may  be  necessary.  When 
not  needed  for  this  purpose  they  perform  other  assigned 
duties. 


200  MILITARY  SIGNAL  CORPS  MANUAL 

The  messengers  perform  the  duties  of  linemen  during  the 
installation  of  the  system.  After  this  is  completed  they  per- 
form such  messenger  service  as  is  necessary  in  connection 
with  the  telephone  central. 


NUMERICAL   DESIGNATION    OF    MEMBERS 

332.  The  men  of  the  telephone  section,  except  the  chief  of 
section  chief  operator,  and  chief  lineman,  are  numbered  from 
1  to  15  for  the  purpose  of  prescribing  their  positions  and  duties 
in  various  drills  and  formations. 

Specifically  they  are  divided  in  squads  and  numbered  as 
follows : 

Switchboard  squad : 

Chief  operator,  in  charge. 

1.  Corporal,  switchboard  operator. 

2.  Private,  first  class,  lineman. 

3.  Private,  lineman. 

4.  Private,  first  class,  driver. 
First  line  squad: 

5.  Private,  first  class,  lineman. 

6.  Corporal,   switchboard   operator,   in   charge. 

7.  Private,  first  class,  lineman. 

8.  Private,  messenger. 
Truck  squad : 

9.  Private,  first  class,  driver. 

10.  Corporal,   switchboard   operator,   in   charge. 

11.  Private,  first   class,  lineman. 

14.  Private,  first  class,  driver.  , 
Digging  squad : 

Chief  lineman,  in  charge. 

12.  Private,  first  class,  lineman. 

13.  Private,  first  class,  lineman. 

15.  Private,  messenger. 

After  completion  of  duty  in  connection  with  the  intallation 
of  the  switchboard  and  the  erecting  of  the  terminal  pole  a 
second  line  squad  is  formed  as  follows: 

Second  line  squad : 

1.  Corporal,  switchboard  operator,  in  charge. 

2.  Private,   first   class,   lineman. 

3.  Private,  lineman. 

4.  Private,  first   class,  driver. 

The  section  is  formed  so  as  to  preserve  the  integrity  of  the 
above-named  squads. 


THE  TELEGRAPH  COMPANY  201 


FORMATION   OF   THE   SECTION 


333.  The  section  is  formed  in  line  in  double  rank  with  the 
odd  numbers  in  the  rear  rank  and  even  numbers  in  the  front 
rank.  The  chief  of  section  is  2  yards  in  front  of  the  center  of 
his  section  and  the  drivers  in  the  line  of  file  closers. 


POSTS    OF    INDIVIDUALS 


334.  Positions  of  all  individuals  are  shown  in  accompanying 
plate. 

The  formation  in  park  is  identical  with  that  of  the  tele- 
graph section,  the  trucks  being  formed  from  right  to  left  as 
follows:  No.  1,  switchboard;  No.  2,  wire;  No.  3,  lance. 


DISTRIBUTION    OF    MATERIEL    FOR    TRANSPORT 

335.  This  is  assigned  in  accordance  with  the  principles  which 
govern  the  distribution  of  loads  in  the  telegraph   section. 

Specifically,  the  section  carriages  are  loaded  as  follows: 

Truck  No.  1 :  All  materiel  of  the  section  except  that  car- 
ried on  trucks  2  and  3. 

Truck  No.  2:  All  wire  of  section. 

Truck  No.  3:  Three  hundred  lance  poles  and  necessary  in- 
sulators therefor. 

TO   FORM    THE   SECTION 

336.  The  section  is  formed  in  a  similar  manner  to  the  tele- 
graph section. 

On  account  of  the  small  number  of  men  present  with  the 
telephone  section,  the  chief  makes  such  assignments  and  de- 
tails for  truck  loading  as  will  best  facilitate  the  work. 

MANEUVER 

337.  The  section  is  maneuvered  by  the  same  commands  and 
in  accordance  with  the  same  principles  as  the  telegraph  section. 

TECHNICAL  DRILL 
General  Provisions 

338.  The   general   provisions   governing  the   construction   of 
lance-pole  telegraph   lines  apply  to  telephone  work. 

It  is  almost  impossible  to  construct  a  thoroughly  substantial 


202  MILITARY  SIGNAL  CORPS  MANUAL 

twisted  pair  line  on  lance  poles.  The  load  limit  of  the  trans- 
portation furnished  does  not  permit  the  carrying  of  the  re- 
quisite number  of  lance  poles  necessary  to  support  the  entire 
system.  For  the  above  reasons  advantage  should  be  taken  to 
utilize  every  stable  support  about  the  camp  to  carry  the  lines. 
The  survey  for  the  system  should  be  almost  entirely  based 
upon  the  making  use  of  the  natural  and  artificial  features 
available. 

339.  If  conditions  permit,  all  or  a  portion  of  the  line  may  be 
placed  underground.     The  climatic  conditions  and  character  of 
the   subsoil    will   determine   whether   or   not    this    method   will 
give    practical    results ;    if    adopted,    means    for    protecting   the 
underground  lines  at  road  crossings  should  be  provided. 

340.  The  proper   erection   of  the   divisional  camp   telephone 
system  will  generally  call  for  more  ingenuity  and  improvised 
expedients  than  are  usually  necessary  in  the  construction  of 
the  typical  section  telegraph  line. 


Preliminary  Reconnaissance 

341.  The  construction  of  any  telephone   system,  permanent 
or  temporary,  involves  a  more  or  less  extended  reconnaissance 
of  the  site  where  the  system  is  to  be  located.     Only  after  such 
reconnaissance  is  made  can  an   intelligent  plan  be  formulated 
for  the  erection  of  the  system. 

On  receipt  of  orders  to  install  the  system  at  a  certain  loca- 
tion, the  chief  of  section  and  chief  lineman  will  proceed  at 
once,  by  motorcycle  to  the  point  designated  to  make  the  re- 
quired reconnaissance. 

342.  In  conducting  the  reconnaissance  all  possible  assistance 
will   be   rendered   by   the   camp    commander   or   others   on   the 
ground,  in  the  matter  of  supplying  information  as  to  the  loca- 
tion of  telephone  stations  and  other  necessary  data. 

343.  After  the  reconnaissance  is  complete  an  intelligent  plan 
for  the  erection  of  the  system  will  be  formulated,  supplemented 
by  a  sketch.    This  should  show  the  location  of  the  central  and 
all  telephone  stations ;  the  routes  to  be  followed  by  the  various 
lines;  the  character  of  supports  for  the  same  with  the  neces- 
sary cabling,  and  any  underground  sections  of  the  line,  if  such 
be  decided  upon. 

344.  Reconnaissance  is  imperative  before  any  work  is  com- 
menced.    If  arrangements  can  not  be  perfected  to  accomplish 
it  before  the  arrival  of  the  section  on  the  ground,  construction 
work  will  have  to  be  postponed  until  it  is   complete.     In   the 
latter  case  it  may  be  more  or  less  hurried  but  in  no  case  can 
it  be  omitted. 


THE  TELEGRAPH  COMPANY  203 

345.  Whenever  the  chief  of  section  leaves  the  section  for  this 
or  any  other  necessary  purpose,  the  section  will  be  conducted 
en   route  or  perform  any  other  assigned  duty  under  direction 
of  the  chief  operator  or  other  senior  noncommissioned  officer 
in  charge. 

To  Prepare  to  Open  Station 

346.  When  the  section  has  arrived  at  the  camp  site  at  which 
it  is  to  install  the  system,  the  necessary  reconnaissance  hav- 
ing been   made  and  the  plans  for  the  erection   of  the  system 
formulated,  it  is  parked  at  a  point  convenient  to  the  location 
of  the  central.    The  chief  of  section  then  commands :  PREPARE 
TO   OPEN    STATION.     At    this    command    all   dismount    from 
the    carriages    and    each    member    provides    himself    with    the 
proper  equipment  incident  to  his  employment  in  the  work.    The 
section   is    then    formed   in   line   by    the   chief   of   section   who 
verifies  the   men,  the   individual   equipment  of  each  and  gives 
such  instructions  as  are  necessary  regarding  the  character  and 
order  of  construction  of  the  various  radiating  lines. 

To  Open   Station 

347.  At  the  completion  of  the   necessary  preliminary  direc- 
tions, the  chief  of  section  gives  the  command  OPEN  STATION. 
At  this  command  construction  work  is  begun,  the  system  being 
erected  generally  as  follows : 

The  switchboard  squad  unloads  the  switchboard  truck  at 
the  proper  location  of  central;  it  sets  up  the  switchboard  in 
the  designated  shelter,  erects  the  terminal  pole  and  connects 
the  lines  to  the  board  as  soon  as  available. 

The  digging  squad  digs  holes  to  receive  the  poles. 

The  truck  squad  drops  poles  fitted  with  insulators  at  points 
convenient  to  their  erection  and  lays  the  necessary  wire. 

The  line  squad  or  squads  follow,  erecting  the  line,  pulling  up 
slack,  tieing,  guying,  and  tamping.  The  specific  duties  of  the 
various  squads  in  the  erection  of  the  system  are  as  follows: 

Switchboard  squad:  Unloads  switchboard  truck,  sets  up 
switchboard  and  erects  terminal  pole.  Connects  all  loose  lines 
at  pole  on  completion  of  erection  of  same.  The  work  in  con- 
nection with  the  board  being  complete,  Xos.  1,  2,  3,  and  4, 
under  charge  of  No.  1,  become  a  second-line  squad  and  report 
to  the  chief  of  section  for  assignment  to  duty  in  erecting  lines. 
After  completion  of  the  central  station  the  chief  operator  in- 
stalls and  connects  all  telephones  at  the  various  places  as  fast 
as  the  several  lines  from  the  board  to  each  are  intact.  He 


204  MILITARY  SIGNAL  CORPS  MANUAL 

also  connects  into  the  board  any  loose  line  at  any  time  found 
at  the  terminal  pole. 

Truck  squad:  Nos.  10  and  14,  with  truck  No.  3,  drop  lance 
poles  fitted  with  insulators  at  points  convenient  for  erection  ; 
also  drop  guys  and  stakes  at  proper  points  for  use.  Nos.  9  and 
11,  with  truck  No.  2,  lay  the  lines  from  the  reel  attached  to 
the  rear  end  of  the  truck. 

Digging  squad:  Under  supervision  of  the  chief  lineman  digs 
holes  to  receive  lances  or  other  supports  to  be  used  in  erection 
of  the  line.  When  all  work  of  digging  is  completed  the  digging 
squad  becomes  a  third  line  squad  and  proceeds  to  perform 
such  erecting  work  as  may  be  assigned  -to  it. 

Line  squad:  Erects  poles,  stretches  wire,  ties  in,  guys,  and 
tamps. 

The  duties  of  the  separate  individuals  of  the  section  except 

as  above  described  are  not  definitely  specified.     The  members 

of   the    various    squads    are    assigned   by    their    chiefs    to    such 

therewith  as  may   be   necessary  to    facilitate 

the  work. 

To  Prepare  to  Close  Station 

348.  Pre\iminary    to    the    recovery    of   the    system    it    is    as- 
sumed that  sufficient  notice  will  be  given  the  section  to  allow 
it  to  break  camp  and  properly  dispose  of  the  individual  equip- 
ment of  its  members. 

This  having  been  done  and  the  trucks  parked  at  a  point 
convenient  to  central,  the  chief  of  section  commands :  PRE- 
PARE TO  CLOSE  STATION.  At  this  command  the  section 
forms  similarly  as  in  preparing  to  open  station.  Detailed  in- 
structions and  directions  are  then  given  the  section  relative 
to  the  recovery  of  the  lines. 

To  Close  Station 

349.  All   preliminary   arrangements   having   been    completed, 
to  recover  the  system,  the  chief  of  section  commands  :  CLOSE 
STATION. 

The  line  is  generally  recovered  as  follows: 

The  switchboard  and  telephones  are  disconnected,  recovered, 
and  packed  away,  together  with  all  miscellaneous  material  on 
the  switchboard  truck.  The  poles  are  taken  down  and  loaded 
on  the  proper  trucks.  The  wire  is  reeled  up,  bound  in  suitable 
coils,  and  loaded  on  the  wire  truck. 

The  specific  duties  of  the  various  squads  in  the  recovery  of 
the  system  is  as  follows: 


77/7-   TELEGRAPH  COMPANY  205 

Switchboard  squad:  Chief  operator  and  No.  2  disconnect  the 
switchboard  and  prepare  it  for  loading.  Also  disconnect,  re- 
cover, and  pack  all  telephones,  bringing  in  same  to  switchboard 
station  in  motorcycle  and  side  car.  Nos.  1,  2  and  4  recover 
the  allotted  quota  of  lances  and  insulators  (all  over  300)  to  be 
carried  on  truck  No.  1,  and  load  same.  Truck  No.  1  is  then 
brought  to  the  central  station,  and  the  terminal  pole  is  taken 
down,  if  to  be  recovered.  All  supplies  carried  by  truck  No.  1 
are  then  loaded  on  it  by  the  entire  switchboard  squad  under 
the  direction  of  the  chief  operator. 

Line  squad:  Assisted  by  No.  12,  removes  poles  and  unties  the 
line  therefrom.  Recovers  all  guys  and  such  stakes  as  may  be 
ordered. 

Truck  squad:  No.  10,  assisted  by  No.  13,  removes  insulators 
from  poles  and  loads  poles  and  insulators  on  truck  No.  3. 

No.  11,  assisted  by  No.  15,  reels  up  wire,  ties  same  in  proper 
sized  coils,  and  then  loads  on  truck  No.  2. 

If  necessary  to  expedite  the  work  of  recovering  the  wire, 
truck  No.  1,  after  being  loaded,  will  reel  up  wire,  using  for  this 
purpose  the  extra  reel  operated  by  members  of  the  switch- 
board  squad. 

350.  The    above    assignment    of    construction    duties    to    the 
various  members  of  the  section  is  intended  as  a  guide,  but  one 
which    should  be   generally  followed   in   erecting  the   lines   on 
lances.    Where  other  supports  for  the  lines  are  used,  the  chief 
of   section   will   make   such    changes    in    assignments   of   duties 
as  the  use  of  different  material  requires. 

To  Work  With  Reduced  Numbers 

351.  The  following  is  prescribed  as  a  guide  for  constructing 
and  recovering  the  divisional  telephone  system  when  for  any 
reason  the  section  is  reduced  below  its  normal  quota. 

CONSTRUCTION 

352.  For  17   men. — Omit  chief  operator.     No.   1   acts  as  chief 
operator    in    addition    to    his    other    duties.      Telephones    are    not 
installed    until    line   completed    unless  'other    arrangements    can    be 
made. 

For  16  men. — Omit  No.  3.  Nos.  1,  2,  and  4  constitute  switch- 
board squad.  After  completion  of  duties  at  the  board  become 
second-line  squad  of  three  men;  are  assisted  when  necessary  by 
chief  of  section. 

For  15  men. — Omit  No.  2.  Switchboard  squad  consists  of  Nos. 
1  and  4.  First-line  squad  assists  in  erection  of  terminal  pole. 
After  completion  No.  1  installs  telephone;  No.  4  joins  first-line 
squad.  No  second-line  squad  is  formed. 

For  11  men. — Omit  No.  8. 


206  MILITARY  SIGNAL  CORPS  MANUAL 

For  IS  men. — Omit  No.  1.  No.  6  acts  as  chief  operator.  First- 
line  squad  takes  over  duty  of  switchboard  squad  entire  in  addi- 
tion to  other  duties. 

For  IS  men. — Omit  No.  15. 

For  11  men. — Omit  No.  10.  No.  14  puts  off  poles  in  addition 
to  driving  his  truck. 

For  10  men. — Omit  No.  11.  Trucks  Nos.  2  and  3  alternate  in 
laying  wire  and  dropping  poles  as  may  be  necessary.  Nos.  9 
and  14  attend  each  truck  separately,  other  truck  remaining  idle. 

For  9  men. — Omit  chief  lineman.  Chief  of  section  performs 
his  duties. 

For  8  men. — Omit  No.  12.  Switchboard  and  first  line  squad 
are  combined,  consists  of  Nos.  4,  5,  6,  and  7.  Truck  squad  and 
digging  squad  are  combined,  consists  of  chief  of  section,  Nos. 
9,  13,  and  14.  Squads  perform  duties  alternately  as  may  be 
necessary. 

For  7  men. — Omit  No.  13.  Chief  of  section  and  No.  9  man 
wire  truck  in  laying  wire  and  No.  14  drops  off  poles  in  addition 
to  driving  truck. 

For  6  men. — Omit  No.  6.  Chief  of  section  performs  his  duties. 
Trucks  Nos.  2  and  3  alternate  in  laying  wire  and  dropping  poles. 
Nos.  9  and  14  attend  each  truck  separately,  leaving  other  truck  idle. 

For  5  men  or  less. — The  duties  are  performed  in  rotation  by 
the  squads  as  may  be  necessary  to  best  facilitate  the  work.  Four 
men  is  the  minimum  number  which  can  install  the  system. 

RECOVERY 

353.  For  17  men.— Omit  No.  12. 

For  16  men. — Omit  No.  3. 

For  15  men. — Omit  No.  8.     Chief  lineman  takes  his  place. 

For  14  men. — Omit  No.  7. 

For  13  men. — Omit  chief  operator.  Chief  of  section  takes  his 
place. 

For  12  men. — Omit  No.  2.  Nos.  I  and  4  assist  chief  of  section 
in  preparing  switchboard  for  loading  before  recovering  poles. 
Chief  of  section  recovers  telephones  alone. 

For  11  men.— Omit  No.*  13. 

For  10  men. — Omit  No.  5. 

For  9  men. — Omit  No.  10.  No.  9  recovers  poles  in  addition  to 
driving  truck. 

For  8  men. — Omit  No.  15.  No.  9  takes  his  place.  Trucks  Nos. 
2  and  3  alternate  in  loading  poles  and  reeling  in  wire. 

For  7  men. — Omit  No.  11.  Chief  of  section,  Nos.  1,  4,  9,  and 
14  perform  duties  of  switchboard  squad  on  completion  of  which 
the  poles  are  loaded  and  wire  reeled  in  simultaneously  by  two 
trucks  assigned  to  these  duties  by  chief  of  section. 


THE  TELEGRAPH  COMP.IXY  207 

For  6  men. — Omit  No.  1. 

For  5  men  or  less. — Duties  incident  to  recovery  are  performed 
in  rotation  by  the  squads  as  is  necessary  to  best  facilitate  the 
work.  Three  men  are  the  minimum  number  which  can  recover 
the  system. 

LINE   CONSTRUCTION 

In  the  construction  of  the  semi-permanent  divisional  system 
the  following  directions  should  be  carefully  observed. 

Use  of  Lance  Poles 

Lance  poles  will  only  be  used  when  no  better  line  supports 
are  available.  Every  local  advantage,  such  as  trees,  tent  poles, 
and  telegraph  poles  should  be  utilized  in  construction  work. 
Similarly,  cut  logs,  poles,  heavy  timbers,  or  other  suitable 
lumber  in  the  vicinity  of  the  camp  should  be  substituted  for 
lances  wherever  possible. 

If  lance  poles  are  used,  one  pole  is  erected  for  each  twisted 
pair  carried,  up  to  a  maximum  of  four  poles.  Where  more 
than  one  pole  is  used  for  this  purpose,  the  poles  will  be  tightly 
lashed  with  No.  14  GI  wire  or  other  material  of  equal  strength. 
If  two  poles  are  used  together  they  should  be  lashed  in  three 
places;  once  at  each  end  and  once  in  the  middle.  Clusters  of 
three  or  four  poles  should  have  four  lashings.  In  all  cases 
the  top  lashing  should  be  flush  with  iron  pole  tip. 

Poles  should  be  spaced  at  distances  not  to  exceed  the  follow- 
ing: 35  yards  when  one  or  two  pairs  are  carried;  30  yards 
when  three  to  five  pairs  are  carried;  and  25  yards  when  five 
to  eight  pairs  are  carried. 

Cabling 

All  lines  will  be  cabled  wherever  practicable,  as  a  stronger 
system  and  one  less  liable  to  damage  from  camp  traffic  is  gained 
thereby.  Eight  pairs  is  the  maximum-sized  cable  which  should 
be  carried  on  lances.  Up  to  three  pairs  the  lines  may  be 
cabled  by  three  lashings  of  marlin  or  insulated  wire  spaced 
at  equal  distances  between  supports.  If  a  line  consists  ot 
more  than  three  pairs,  it  should  be  cabled  throughout  with 
marlin. 

Depth  of  Poles 
Lances  should  be  sunk  to  a  depth  of  14  to  20  inches  depending 


208  MILITARY  SIGNAL  CORPS  MANUAL 

on  the   size  of  the  cluster.     Fourteen  inches  is   the  minimum 
depth  for  a  single  lance  pole. 

Terminal  Poles 

If  practicable,  some  form  of  terminal  pole  should  be  rigged 
up  and  carried  with  the  section.  Such  a  pole,  if  of  sufficient 
size  and  properly  guyed,  can  be  rigidly  set  up  flush  with  the 
ground.  If  no  terminal  pole  is  carried  every  effort  should  be 
made  to  secure  a  suitable  piece  of  material  from  which  to 
make  one  on  arrival  at  the  location  for  the  erection  of  the 
system.  Failing  in  this,  five  lance  poles  heavily  lashed  will 
answer  as  a  terminal  pole.  In  all  cases  terminal  poles  should 
be  framed  with  brackets  and  insulators  before  erection  and 
should  be  strongly  guyed  four  ways. 

Guying  and  Guy  Stakes 

On  straight  stretches  lances  should  be  guyed  both  ways, 
as  follows  :  Every  fifth  pole  carrying  one  or  two  pairs ;  every 
third  pole  carrying  from  three  to  five  pairs ;  every  pole  carry- 
ing more  than  five  pairs.  For  guying,  if  using  No.  14  iron  wire, 
guys  should  be  made  up  to  allow  one  strand  of  iron  wire  for 
each  twisted  pair  carried  on  the  pole.  If  No.  9  wire  is  avail- 
able a  single  strand  will  suffice  in  all  save  exceptional  cases. 
No.  9  double  will  take  care  of  any  case.  Every  corner  should 
be  guyed  against  the  strain  according  to  the  above  principles. 

Guy  stakes  as  needed  should  be  improvised  from  material 
found  in  the  vicinity  of  the  camp.  The  utilization  of  every 
possible  means  along  the  lines  to  which  guys  can  be  anchored 
will  limit  the  number  of  guy  stakes  necessary. 

Insulators 

One  insulator  fitted  to  single  or  double  lances  and  two 
to  triple  or  quadruple  clusters  should  be  used.  As  many  pairs 
as  possible  should  be  split  over  the  insulator  before  the  tie  is 
made.  A  tie  of  at  least  four  wraps  of  insulated  wire  on  each 
side  of  the  insulator  is  made  on  every  pole. 

To  Take  Up  Slack 

Stretch  the  wire  as  tautly  as  possible  to  the  pole  about  to 
be  erected,  which  is  laid  on  the  ground  about  15  inches  short 
of  the  hole.  The  strength  of  two  men  without  blocks  or  rope 
is  sufficient  for  this  purpose.  Make  the  tie  and  erect  the 


THE  TELEGRAPH  COMPANY  209 

pole.    The  pole  should  then  stand  absolutely  erect  and  the  line 
have  no  excess  slack. 


OPERATION  AND  MAINTENANCE 

The  operation  and  maintenance  of  the  divisional  system 
should  give  little  trouble  if  proper  care  is  used  in  installation. 

The  switchboard  operators  operate  the  board  on  a  24- 
hour  shift,  if  necessary,  supervised  by  the  chief  operator.  At 
least  two  competent  linemen  should  be  on  duty  continuously 
during  the  day  at  central  to  make  immediate  repairs  to  tele- 
phones or  remove  any  apparent  line  trouble. 

If  the  system  is  immobilized,  by  an  order  for  the  section 
to  perform  duty  elsewhere,  four  men,  including  the  chief  opera- 
tor, should  be  left  to  care  for  the  system,  any  necessary  as- 
sistance being  given  them  in  this  work  by  details  of  line 
troops.  A  withdrawal  of  the  section  entire  from  the  erected 
system  should  never  be  done  except  in  grave  emergency.  In 
such  a  case  at  least  one  man,  preferably  the  chief  operator, 
should  be  left  with  the  system,  timely  arrangements  being 
made  to  secure  a  competent  detail  from  other  troops  to  sub- 
stitute for  the  regular  operation  and  maintenance  crew. 

As  soon  as  the  system  is  erected  and  is  in  working  order, 
the  chief  of  section  and  chief  lineman  make  a  minute  and 
careful  inspection  of  the  whole.  All  apparent  defects  will  be 
at  once  corrected  and  every  expedient  possible  calculated  to 
strengthen  the  lines  or  preclude  trouble  thereon  will  be  utilized. 


UNDERGROUND    CONSTRUCTION 

When  necessary  or  desirable  to  place  all  or  part  of  the 
system  underground  the  following  notes  may  be  found  useful. 

Trenching 

This  can  best  be  done  with  a  gang  of  pick-and-shovel  men. 
This  method  is  very  slow  unless  there  is  a  large  detail  equipped 
with  digging  tools  to  assist  the  section  in  this  work.  A  plow 
is  included  with  each  section  equipment  for  this  purpose  and 
should  be  ordinarily  used  to  turn  out  a  furrow  trench.  The 
plow  is  used  attached  to  a  truck  which  furnishes  tractive  power 
therefor.  The  plow  should  be  fastened  so  as  to  tow  directly 
behind  the  middle  of  the  truck  at  a  distance  of  about  8  feet. 
In  moist  soil  it  will  be  found  necessary  to  employ  mud  chains 
on  the  wheels  to  get  sufficient  traction.  Unless  the  plow  used 
turns  a  furrow  10-12  inches  deep,  a  second  plowing  to  deepen 


210 

the  trench  is  necessary.  All  loose  dirt  in  the  furrow  trench 
should  be  removed  by  shovel  men.  After  this  the  trench  may 
be  improved  if  desired  by  driving  a  truck  with  a  hind  wheel 
following  therein,  this  making  a  emooth  flat  bottom. 

Cabling 

When  more  than  one  pair  is  trenched  the  wires  should  be 
cabled  up  to  3  pairs ;  ties  at  10-foot  intervals  will  be  found 
sufficient.  Above  three  pairs  the  wires  should  be  cabled 
throughout. 

Covering 

This  is  not  practicable  with  the  plow.  It  should  be  care- 
fully done  with  shovels  and  packed  as  tightly  as  possible;  after 
which  a  truck  should  be  run  along  the  trench  to  complete  the 
tamping. 

Guards 

Guards  of  timber,  logs,  old  pipe,  or  any  suitable  material 
should  be  employed  to  protect  the  trench  at  all  road  crossing's 
and  other  points  of  apparent  danger.  Due  to  the  inferior  grade 
of  insulation  the  greatest  care  must  be  used  in  handling  wires 
throughout  construction  to  eliminate  the  possibility  of  short 
circuits  and  subsequent  line  trouble. 

THE  PLATOOX 
FUNCTION  AND  ORGANIZATION 

354.  The  platoon   consists  of  two  sections.     These  sections 
may  be  both  telegraph,  both  telephone,  or  one  of  each.    Neces- 
sarily, therefore,  the  function  of  the  platoon  is  so  variable  that 
no  accurate  description  of  it  is  possible. 

A  platoon  is  commanded  by  a  first  lieutenant,  who  is  re- 
sponsible for  its  efficiency  while  attached  to  the  company,  and 
who  supervises  its  technical  work  when  detached  for  duty. 
He  is  specially  charged  with  the  necessary  supply  cf  his 
sections  wherever  his  platoon  is  dctarhed. 

FORMATIONS 

355.  Platoon  formations  are  but  combinations  of  the  normally 
formed    sections.     In   park   the   platoon    may   be    arranged   in 


THE  TELEGRAPH  COMPANY  211 

either  of  two  ways,  as  follows :  Sections  in  line  abreast  of 
each  other  at  5  yards  interval;  sections  in  line  one  behind 
the  other  at  10  yards  distance.  The  decision  as  to  which  for- 
mation will  be  taken  will  usually  depend  on  the  ground  avail- 
able. In  either  case  the  post  of  the  platoon  chief  is  5  yards 
in  front  of  the  center  of  his  platoon. 

356.  In  column   of   route   the;  sections  follow   each   other  in 
the  order   prescribed   by   the   platoon   chief.     The   post   of  the 
platoon  chief  is  normally  25  yards  in  front  of  the  leading  car- 
riage of  the  leading  section.     Otherwise  he  goes  wherever  his 
presence    is    necessary.     A    minimum    distance   of   25    yards    is 
prescribed  between   sections  on  the  road. 

TO    FORM    THE    PLATOON 

357.  The  sections  are  formed  by  their  chiefs  as  prescribed 
in  paragraph  306,  the  kind  of  park  formation   desired  having 
been  previously  indicated  by  the  platoon  chief. 

On  completion  of  the  inspection  by  the  chief  of  section  they 
report  to  the  platoon  chief  from  right  to  left,  or  front  to  rear, 
according  to  the  formation ;  (Such)  Section,  IN  ORDER, 
SIR,  or  if  anything  missing  or  out  of  order  they  so  report. 

MANEUVER 

358.  The   platoon   is   maneuvered   in   accordance   with   prin- 
ciples prescribed  for  the   section. 

TECHNICAL    DRILL 

359.  There  is  no  technical  drill  prescribed  for  the  platoon  as 
such.    The  section  is  the  largest  unit  which  can  operate  techni- 
cally in  a  single  location. 

METHODS   OF   EMPLOYMENT 

360.  The  functions  of  the  platoon  vary  so  greatly  that  any 
well-defined  method  of  employment  can  not  be  stated. 

A  telegraph  platoon  will  ordinarily  be  assigned  to  semi- 
permanent line  building  the  extent  of  which  makes  the  em- 
ployment of  more  than  one  section  unit  desirable.  Again,  it 
may  operate  for  some  time  an  extended  system  of  a  semi-per* 
manent  line.  In  the  first  case  the  platoon  chief  acts  as  con- 
struction superintendent,  co-ordinating  the  work  of  the  sec- 
tions and  providing  for  their  timely  supply  of  technical  material. 
In  the  latter  case  he  acts  as  superintendent  of  operation  and 


212  MILITARY  SIGNAL  CORPS  MANUAL 

maintenance  with  reference  to  the  line  operated  by  his  pla- 
toon. It  may  happen  that  the  sections  do  not  construct  or 
operate  in  contiguous  fields.  In  this  case  he  is  charged  with 
general  supervision  of  each. 

A  telephone  platoon  necessarily  performs  its  functions  with 
its  sections  located  in  different  theaters  of  operations.  Gen- 
eral and  intermittent  supervision  of  construction,  operation, 
and  supply  is  in  this  case  the  role  of  the  platoon  chief. 

Operations  carried  on  by  mixed  platoons  will  usually  par- 
take of  a  combination  of  telegraph  and  telephone  section  work 
and  will,  in  general,  be  governed  by  the  principles  laid  for  the 
handling  of  these  units. 

THE  COMPANY 

FORMATIONS  AND  POSTS  OF  INDIVIDUALS 

361.  The  company  is   formed  in  line  or  in  column  of  route. 

362.  It  is  in  line  when  the  platoons,  with  their  sections  in 
line  one  behind  the  other,  are  formed  abreast  of  each  other. 

363.  It    is    in   column    of   route   when   the   platoons,   each   in 
column    of    sections    in   road   formation,   follow    each    other    in 
such  order  as  may  be  directed. 

364.  The  company  is  habitually  parked  in  line,  the  carriages 
of  the   captain   and  platoon   chiefs   being  parked  on   the   right 
of  those  of  the  headquarters  messengers. 

Sections  1  and  2  are  telegraph  sections;  sections  3  and  4, 
telephone  sections.  Normally  sections  1  and  2  constitute  the 
first  platoon  and  sections  3  and  4  the  second  platoon.  The 
integral  sections  of  the  platoon  may  be  varied  by  the  com- 
pany commander  when  necessary. 

The  drawing  shows  the  formation  of  the  company  in  line  and 
in  column  of  route. 

The  transportation  assigned  to  company  headquarters  con- 
sists of  1  inspection  car  (company  commander),  5  motorcycles 
with  side  cars  (1  each  platoon  chief,  1  first  sergeant,  and  2 
messengers),  and  1  headquarters  truck. 

The  personnel  of  company  headquarters  (less  drivers  of 
carriages  of  captain  and  platoon  chiefs)  are  transported  as 
follows :  Motorcycle  No.  1,  first  sergeant  and  sergeant  me- 
chanic; motorcycles  Nos.  2  and  3,  messengers  and  master  sig- 
nal electricians;  company  headquarters  truck,  mechanics,  horse- 
shoer,  and  clerk.  The  supply  and  mess  sergeants  and  the  cooks 
are  carried  on  the  field  transportation. 

TO    FORM    THE    COMPANY 

365.  The  company  is  formed  by  the  first  sergeant,  the  sec- 


THE  TELEGRAPH  COMPANY  213 

tions  falling  in  in  order  of  their  numbers  from  right  to  left,  as 
prescribed  in  forming  the  company  dismounted,  after  which 
he  commands :  By  section,  FALL  OUT.  The  procedure  out- 
lined in  paragraphs  306  and  333  is  followed  by  the  sections. 

The  first  sergeant  forms  the  company  in  line  and  takes  his 
post. 

Each  platoon  chief,  having  received  the  report  of  his  sec- 
tion chiefs,  makes  a  general  inspection  of  his  platoon  and  com- 
mands :  REST. 

Upon  the  approach  of  the  captain,  the  platoon  chiefs  call 
their  platoons  to  attention,  and  as  soon  as  the  captain  takes 
his  place  in  front,  report  in  succession  from  right  to  left: 
(SUCH)  PLATOONS  IN  ORDER,  SIR;  or  if  anything  is  miss- 
ing or  out  of  order  they  so  report.  As  soon  as  the  platoon 
chiefs  have  reported  to  the  captain,  the  first  sergeant  reports 
to  the  captain  as  prescribed  in  forming  the  company  dis- 
mounted. 

The  enlisted  personnel  of  company  headquarters  forms 
when  the  first  sergeant  takes  his  post  as  follows  :  Master  sig- 
nal electricians  and  messengers  dismounted  in  front  of  their 
respective  carriages  and  on  line  with  front  dismounted  rank 
of  foremost  sections ;  personnel  of  headquarters  truck,  first 
sergeant,  and  sergeant  mechanic  dismounted  in  double  rank 
on  line  with  dismounted  ranks  of  rearmost  sections,  first  ser- 
geant on  the  right. 

On  the  approach  of  the  captain  the  platoon  chiefs  and  their 
drivers  post  themselves  dismounted  facing  to  front  beside 
their  respective  carriages ;  platoon  chiefs  on  the  right,  drivers 
on  the  left.  The  captain  dismounts  to  receive  the  report  of 
the  platoon  chiefs. 

TO  DISMISS  THE  COMPANY 

366.  The    company   being   in    line   and   the   personnel   being 
mounted  on  the  carriages    the    captain    commands :     DISMISS 
THE  COMPANY.     The  platoon  chiefs  and  master  signal  elec- 
tricians fall  out,  their  carriages  being  parked  in  proper  place 
by  the   drivers.     The  first  sergeant  takes   charge  of  the  com- 
pany  and   commands :   By   section,  FALL  OUT.     The   sections 
are  dismissed  as  prescribed  in   paragraph  312.     The  personnel 
of  the  headquarters  truck  under  charge  of  chief  mechanic  sees 
to  the  proper  disposal  of  the  headquarters  property  and  there- 
after is  dismissed  by  the  latter. 

MANEUVER 

367.  The  company  is  maneuvered  in  accordance  with  the  prin- 
ciples prescribed  for  the  section  and  platoon. 


214  MILITARY  SIGNAL  CORPS  MANUAL 

En  route  the  captain  may  direct  one  or  both  of  the  platoon 
chiefs  to  march  in  rear  of  the  column,  if  deemed  desirable. 

EMPLOYMENT    IN    THE    FIELD 

368.  There  is  no  technical  drill  for  the  telegraph  company 
as  such.  It  functions  wholly  through  the  operations  of  its 
platoons  or  sections.  Unity  of  action  will  occur  in  case  all 
four  sections  are  assigned  to  contiguous  telegraph  work,  per- 
mitting direct  technical  control  of  all  from  comp.any  head- 
quarters. This,  however,  will  be  exceptional  rather  than  the 
rule  of  employment. 

Sections  or  platoons  generally  function  while  dispersed  and 
isolated,  the  company  headquarters  exercising  the  duties  of 
administration  and  furnishing  reserve  supplies,  material,  and 
technical  assistance  when  needed. 

Telegraph  company  units  will  frequently  be  called  upon  to 
work  over  terrain  not  necessarily  occupied  by  other  troops. 
This  will  require  independent  messing  facilities  and  special 
arrangements  for  supply.  Duties  incident  thereto  pertain  to 
company  headquarters,  the  same  being  facilitated  by  the  pres- 
ence of  motor  transportation. 

The  telegraph  section  carries  one  day's  supply  of  construc- 
tion material  and  only  a  limited  supply  of  operation  material. 
Timely  arrangements  must  be  made  by  company  headquarters 
for  a  steady  daily  flow  of  technical  materiel  to  the  section  it 
they  are  to  be  kept  employed.  Well-defined  plans  for  this 
work  will  be  formulated  on  receipt  of  orders  detaching  a  sec- 
tion or  platoon  for  duty. 

The  supply  of  reserve  materiel  in  the  company  is  practically 
nil.  Requisitions  through  the  battalion  commander  to  the 
advanced  signal  depot  should  be  wired  in  as  soon  as  the  need 
is  apparent.  These  requisitions  should  state  amounts  desired 
and  the  times  and  places  of  delivery.  Ordinarily  transporta- 
tion should  be  furnished  by  the  Quartermaster  Corps  but  un- 
less the  same  is  assured,  any  motor  carriages  which  are  idle 
should  be  used  for  the  purpose,  if  necessary  calling  on  the 
battalion  commander  for  assistance.  It  will  frequently  happen 
that  all  the  sections  of  the  company  are  not  engaged  in  work 
at  the  same  time.  In  this  case  idle  sections  should  be  utilized 
locally  to  supply  those  at  work. 

Telegraph  companies,  especially  when  engaged  in  telegraph 
work  proper,  differ  materially  from  field  companies  from  the 
fact  that  the  former  lay  semi-permanent  and  the  latter  wholly 
temporary  lines.  The  general  role  of  the  telegraph  company 
headquarters  is  administrative,  but  whenever  practicable,  it 
co-ordinates  the  work  of  its  units.  Its  prime  factor  is  their 
proper  maintenance  and  supply. 


THE  TELEGRAPH  BATTALION 

FUNCTION 

369.  The  telegraph  battalion  is  habitually  assigned  to  duty 
with  the  army  corps.    Its  function  is  to  maintain  communication 
between  the  advanced  base  of  the  corps  and  the  headquarters 
of  the  several  divisional  units  and  to  furnish  such  local  tele- 
phone systems  for  these  units  as  may  be  necessary. 

ORGANIZATION 

370.  The  telegraph  battalion   is  composed  of  one  battalion 
headquarters,  one  supply  detachment,  and  two  telegraph  com- 
panies. 

In  detail  battalion  headquarters  and  the  supply  detachment 
is  as  follows: 
major 

adjutant   (first   lieutenant), 
supply  officer  (first  lieutenant), 
sergeant   major    (sergeant,   first    class), 
supply  sergeant   (sergeant). 
2  drivers  field  train  (privates,  first  class). 

2  clerks    (privates,    first   class). 

3  drivers   officers'   carriages   (privates). 

Total,  commissioned,  3;  enlisted.  9. 

The  transportation  furnished  the  battalion  consists  of  one 
inspection  car,  two  motorcycles  with  side  cars,  and  two  field 
trucks. 

371.  The  major  rides  in  the  inspection  car,  the  adjutant  and 
supply  officer  normally  on  the  motorcycles  or  side  cars.     An 
allowance  of  one  driver  for  each  of  these  carriages  is  provided 
in  the  enlisted  personnel  of  headquarters.    The  remaining  men 
of  battalion  headquarters  personnel  are  carried  on  the  field 
train. 

215 


216  MILITARY  SIGNAL  CORPS  MANUAL 

372.  The  technical  equipment  of  the  battalion  is  very  limited 
in    extent.      It    consists    of    certain    signaling   instruments,    the 
employment    of    which    in    the    telegraph    zone    will   be    excep- 
tional, and  a  few  other  necessary  miscellaneous  articles. 

FORMATIONS   AND  POSTS   OF   INDIVIDUALS 

373.  The  battalion  may  be  formed  in  line  or  in   column  of 
route. 

374.  It    is    in   line    when    the    companies,  each    in    line,    are 
formed  abreast  of  each   other.     The  normal  interval  between 
companies  in  the  battalion  is  10  yards. 

375.  It  is  in  column  of  route  when  the  companies  each  in 
column  of  route  follow  each  other  in  designated  order.     The 
minimum  distance  between   companies   in   column   of  route  is 
50  yards. 

376.  The  posts  of  individuals  in  the  telegraph  battalion  staff 
assimilate    those    of    the    field    battalion,    such    changes    being 
made  as  are  necessary  to  accord  with  the  presence  of  motor 
transportation. 

MANEUVER 

377.  The  formation  of  the  telegraph  battalion  is  wholly  in- 
formal in  nature.     The  major  sends  directions  by  his  adjutant 
as  to  the  character  of  the  formation  and  the  position  of  the 
base  company.     The  battalion  is  then  formed  accordingly  and 
on  completion  thereof  the  adjutant  reports  to  the  major. 

378.  No  specified  maneuvers  are  prescribed  for  the  telegraph 
battalion.     The  major  gives   directions  verbally  or  through   a 
staff  officer   to  the  captains,  so  as  to  cause  the  battalion  to 
take  up  the  desired  formation. 

EMPLOYMENT   OF   THE   BATTALION 

379.  The  telegraph  battalion  performs  its  functions  through 
its  company,  platoon,  and  section  units.     Battalion  headquart- 
ers co-ordinates  the  work  of  the  detached  units  where  neces- 
sary and  renders  to  them  all  assistance  possible  especially  in 
the  matter  of  supply. 

380.  The  battalion  commander  utilizes  companies  or  parts  of 
them  to  assist   others   when   circumstances   demand.     He   acts 
as   technical   inspector   of   all   forms    of   communication    estab- 
lished in  his  zone  and  performs  such  administrative  duties  as 
the  needs  of  his  battalion  require. 


BASE-LINE  SIGNAL  TROOPS 

GENERAL  PROVISIONS 
FUNCTION 

Base-line  signal  troops  are  those  troops  which  furnish  the 
lines  of  information  to  connect  commercial  systems  with  the 
advanced  bases  of  armies  in  the  field  and  which  supplement 
or  supplant  the  latter  service  wherever  and  whenever  neces- 
sary. 

The  function  of  base-line  signal  troops  is  broad  and  varied; 
broad  in  that  it  may  extend  from  the  theater  of  operations  to 
the  seat  of  government  itself;  varied  in  that  it  may  comprise 
any  or  all  forms,  means  and  methods  of  transmitting  informa- 
tion. On  this  account  the  employment  of  these  troops,  except 
in  a  very  general  way,  can  not  be  stated.  They  are  designed  to 
furnish  the  most  suitable  means  of  communication  necessary 
to  complete  the  chain  or  otherwise  supplement  or  supplant 
commercial  systems  in  maintaining  uninterrupted  military  lines 
of  information  at  all  times. 

ZONES  OF  OPERATION 

There  are  none  in  particular  prescribed.  Base-line  signal 
troops  may  operate  all  or  any  part  of  the  inner  strategical 
zone  if  required  to  do  so  in  performing  their  function.  The 
operation  of  these  troops  in  the  outer  strategical  zone  will 
probably  be  occasionally  required  due  to  the  fact  that  they 
gradually  supersede  telepraph  signal  troops  in  advance  and  are 
replaced  by  them  in  retirement.  The  most  usual  theater  of 
operations  for  these  troops  is,  however,  in  that  portion  of  the 
inner  strategical  zone  immediately  in  rear  of  the  telegraph 
signal  troops.  For  in  such  locations  commercial  systems  are 
either  entirely  lacking  or  inadequate  and  reasons  for  systems 
operated  by  troops  greatest.  Base-line  systems  should  not  sup- 
plant regular  commercial  systems  unless  the  latter  cannot 

217 


218  MILITARY  SIGNAL  CORPS  MANUAL 

furnish  satisfactory  service,  or  good  military  reasons  exist  for 
effecting  the  change. 

ORGANIZATION 

Base-line  signal  troops  are  organized  as  telegraph  signal 
troops.  No  regular  equipment  is  specified.  Transportation, 
construction  and  operation  material,  tools,  and  technical  sup- 
plies are  furnished  these  troops  as  the  needs  of  any  special 
situation  may  require.  Base-line  signal  troops  require  a  maxi- 
mum of  civil  technical  skill  and  a  minimum  of  military  train- 
ing. For  this  reason  these  troops  will  probably  be  recruited 
by  organization  entire  from  commercial  companies  and  sub- 
jected to  such  military  training  as  may  be  necessary  to  cause 
them  to  properly  function  as  military  units. 

Base-line  signal  troops  are  administered  by  company  and 
battalion  as  in  the  case  of  other  signal  troops.  While,  as  a 
rule,  these  troops  will  operate  dispersed,  their  location  along 
well-defined  lines  of  communication  render  the  details  of  ad- 
ministration and  supply  comparatively  easy. 

CHARACTER  OF  EMPLOYMENT 
GENERAL  PROVISIONS 

Base-line  signal  troops  are  employed  in  any  way  necessary 
to  effect  or  maintain  communication  within  their  assigned 
sphere  of  operations. 

The  operations  of  these  troops  can  be  divided  generally  into 
two  classes — construction  and  operation,  together  with  neces- 
sary maintenance,  of  systems  already  installed.  Employment 
in  either  field  is  limited  in  extent  only  by  existing  means  and 
methods  for  the  transmission  of  information. 

REPLACEMENT  OF  SEMI-PERMANENT  LINES 

Telegraph  signal  troops  establish  semi-permanent  lines 
only  when  necessary.  Where  permanent  existing  lines  are 
found  within  the  telegraph  zone  their  function  is  solely  that  of 
operation.  When  on  advance  the  telegraph  zone  becomes 
merged  into  the  base-line  zone,  and  the  troops  of  the  latter 
replace  those  of  the  former.  If  desirable,  they  remove  such 
semi-permanent  lines  as  may  be  found.  This  will  probably  be 
done  both  on  account  of  the  unstability  of  construction  of  the 
lines,  and  to  obviate  the  necessity  of  employing  special  instru- 
ments in  their  operation.  Wherever  permanent  lines  exist 
in  this  zone,  base-line  troops  take  over  their  operation. 


BASE-LINE  TROOPS  219 

Base-line  signal  troops  may  be  frequently  called  upon  to 
perform  this  duty,  the  principal  reason  being  to  provide  mili- 
tary supervision,  discipline,  and  control  over  systems  whose 
primary  function  is  the  transmission  of  military  information. 
Arrangements  for  troops  to  replace  civil  personnel  are  made 
by  the  Chief  Signal  Officer  of  the  Army,  under  instructions  of 
the  War  Department.  Such  arrangements  should  provide  for 
taking  over  entire  systems  or  zones,  and  care  should  be  taken 
to  distinctly  segregate  civilian  and  military  operators,  thus 
avoiding  any  conflict  of  authority  or  division  of  responsibility. 

The  replacement  of  civil  by  military  personnel  applies  to 
all  forms  of  systems  of  communication,  telegraph  or  telephone, 
wire,  radio,  or  cable. 

Ordinarily  the  nearer  the  theater  of  active  operations  the 
lines  of  information  approach,  the  more  reason  will  exist  for 
handling  the  same  by  troops  in  preference  to  civilians. 

The  conduct  of  operations  of  base-line  signal  troops  will 
be  in  accordance  with  the  Signal  Corps  manuals,  covering  the 
various  phases  of  permanent  construction  and  operation. 

PORTABLE  RADIO   SYSTEMS 

These  systems  are  distinctly  military  and  may  be  horse 
drawn  or  motorized,  usually  the  latter.  They  will  frequently 
be  used  to  supplement  wire  systems,  both  permanent  and  semi- 
permanent, and  will  usually  be  located  at  various  points  in  the 
outer  portion  of  the  inner  strategical  zone.  Corps  and  Army 
headquarters  will  be  supplied  with  these  sets,  which  will  form 
independent  lines  of  information  between  themselves,  to  divi- 
sional units  in  front  and  to  important  points  in  rear.  These 
systems  will  be  operated  by  base-line  signal  troops  properly 
organized  and  equipped  for  this  service,  under  the  provisions 
established  for  the  operation  of  military  radio  stations  in 
general. 

SUPERVISION  AND  CONTROL 

Base-line  signal  troops  are  organized  into  companies  and 
battalions  in  order  to  permit  proper  supervision  and  control 
in  their  operations.  Sectors  or  areas  will  be  assigned  to  units 
for  construction  or  operation  and  maintenance,  as  the  case 
may  be,  and  the  unit  commander  thereof  charged  with  efficient 
supervision  and  control  therein.  Separate  units  will  be  as- 
signed, if  practicable,  to  function  wholly  within  the  jurisdiction 
of  a  single  higher  commander  to  whose  orders  they  will  be 
subject  for  administration  and  discipline,  and  to  whom  they 
look  for  supply. 

The  signal  officer  of  the  line  of  communications  is  charged 
with  the  technical  supervision  and  inspection  of  base-line  sig- 
nal troops  within  his  jurisdiction. 


DEPOT   SIGNAL  TROOPS 

These  troops  are  organized  into  companies  for  service  in 
peace  and  into  battalions  for  service  in  war. 

In  peace  these  companies  are  primarily  formed  for  the  pur- 
pose of  administration.  The  personnel  performs,  in  general, 
detached  duty  in  connection  with  the  installation,  operation, 
and  maintenance  of  interior  systems  of  communication.  In  so 
far  as  applicable,  they  perform  such  duties  of  base-line  troops 
as  exist  in  peace  time. 

In  war  these  troops  are  organized  into  battalions  as  ad- 
ministrative and  training  units  designed  to  keep  the  ranks  of 
active  organizations  supplied  with  trained  personnel  as  the 
needs  require.  Depot  battalions  in  war  should  be  organized 
on  a  basis  of  one  to  each  Army  corps. 

The  companies  of  depot  battalions  are  composed  as  follows: 
1  captain. 
5  first  lieutenants. 

3  master  signal  electricians. 

1  first    sergeant    (sergeant,   first   class). 
1  supply  sergeant  (sergeant). 
1  stable   sergeant    (sergeant). 

1  mess  sergeant   (sergeant). 

4  mechanics    (corporals). 

2  clerks    (corporals). 
1  horseshoer. 

1  driver   (private,  first  class). 

3  cooks. 

2  buglers. 

1  wire-section   (14  men). 
1  radio  pack  section  (10  men). 
1  radio   wheel    section    (20   men). 
1  outpost  platoon  (21  men). 
1  telegraph  section  (22  men). 
1  telephone  section  (18  men). 
45  recruits  for  training. 

Total,  6  officers  and  170  men. 

The  depot  battalion  is  composed  of  a  headquarters  and 
supply  detachment,  as  prescribed  for  the  telegraph  battalion, 
and  two  depot  companies. 

Active  and  intensive  training  will  be  had  by  classes  de- 
signed to  qualify  men  to  fill  specific  vacancies  whenever  re- 
quisitioned for  by  organizations  engaged  in  duty  at  the  front. 

220 


CEREMONIES 

GENERAL    RULES 

On  occasions  of  ceremony,  except  funerals  and  reviews  of 
large  forces,  troops  will  be  arranged  from  right  to  left  in  line 
and  from  head  to  rear  in  column  in  the  following  order:  First, 
Infantry;  second,  Field  Artillery;  third,  Cavalry. 

Artillery,  Engineers,  and  Signal  Corps  troops,  equipped  as  Infan- 
try, are  posted  as  Infantry;  dismounted  Cavalry  and  Marines 
attached  to  the  Army  are  on  the  left  of  the  Infantry  in  the 
order  named;  companies  or  detachments  of  the  Hospital  Corps 
and  mounted  detachments  of  Engineers  are  assigned  to  places 
according  to  the  nature  of  the  ceremony ;  mounted  companies  and 
detachments  of  signal  troops  are  posted  as  Cavalry.  When  Cavalry 
and  Field  Artillery  are  reviewed  together  without  other  troops  the 
Artillery  is  posted  on  the  left.  Troops  in  column  »in  funeral 
escorts  will  be  arranged  from  head  to  rear  in  the  following 
order :  First,  Cavalry ;  second,  Field  Artillery ;  third,  In- 
fantry. In  the  same  arm,  Regulars,  Militia  in  the  service 
of  the  United  States,  and  Volunteers  are  posted  in  line  from 
right  to  left  or  in  column  from  head  to  rear  in  the  order 
named.  In  reviews  of  large  bodies  of  troops  the  different  arms 
and  classes  are  posted  at  the  discretion  of  the  commanding 
general,  due  regard  being  paid  to  their  position  in  camp.  On  all 
other  occasions  troops  of  all  classes  are  posted  at  the  discre- 
tion of  the  general  or  senior  commanding  officer. 

At  formations  for  ceremony  sabers  are  drawn.  Mounted  of- 
ficers in  facing  toward  the  line  and  in  resuming  their  front 
always  execute  a  left  about. 

Staff  officers,  when  it  is  not  otherwise  prescribed,  draw  and 
return  saber  with  their  chief. 

A  non-commissioned  officer  in  command  of  a  company 
takes  post  on  the  right  of  the  company  in  line  with  it.  After 
aligning  it  he  takes  the  post  of  the  captain  when  the  battalion 
is  in  column. 

221 


REVIEWS 

GENERAL   RULES 

The  adjutant  or  adjutant  general  posts  men  or  otherwise 
marks  the  points  where  the  column  changes  direction,  in  such 
manner  that  the  right  flank  in  passing  the  reviewing  officer 
shall  be  about  10  yards  from  him. 

The  post  of  the  reviewing  officer,  usually  opposite  the  center 
of  the  line,  is  marked  by  a  flag. 

The  reviewing  officer  and  others  at  the  reviewing  stand 
salute  the  standard  as  it  passes ;  when  passing  around  the 
troops,  the  reviewing  officer  and  those  accompanying  him 
salute  the  standard  when  passing  in  front  of  it.  The  review- 
ing officer  returns  the  salute  of  the  commanding  officer  of  the 
troops  only.  Those  who  accompany  the  reviewing  officer  do 
not  salute. 

The  staff  of  the  reviewing  officer  is  in  single  rank,  6  yards 
in  rear  of  him,  in  the  following  order  from  right  to  left :  Chief 
of  Staff,  officers  of  the  General  Staff  Corps,  adjutant  general, 
aids,  then  the  other  members  of  the  staff  in  the  order  of  rank, 
the  senior  on  the  right;  the  flag  and  orderlies  place  them- 
selves 3  yards  in  the  rear  of  the  staff,  the  flag  on  the  right. 

Officers  of  the  same  or  higher  grade  and  distinguished  per- 
sonages invited  to  accompany  the  reviewing  officer  place 
themselves  3  yards  in  rear  of  the  staff,  the  flag  on  the  right. 

Officers  of  the  same  or  higher  grade  and  distinguished 
personages  invited  to  accompany  the  reviewing  officer  place 
themselves  on  his  left ;  their  staff  and  orderlies  place  them- 
selves, respectively,  on  the  left  of  the  staff  and  orderlies  of  the 
reviewing  officer;  all  others  who  accompany  the  reviewing  of- 
ficer place  themselves  on  the  left  of  his  staff,  their  orderlies 
in  rear.  A  staff  officer  is  designated  to  escort  distinguished 
personages  and  to  indicate  to  them  their  proper  positions. 

222 


REVIEWS  223 

When  riding  around  the  troops,  the  reviewing  offices  may 
direct  that  his  staff,  flag,  and  orderlies  remain  at  the  post  of 
the  reviewing  officer  or  that  only  his  personal  staff  and  flag 
shall  accompany  him;  in  either  of  these  cases  the  commanding 
officer  alone  accompanies  the  reviewing  officer.  If  the  review- 
ing officer  is  accompanied  by  his  staff,  the  staff  officers  of  the 
commander  place  themselves  on  the  right  of  the  staff  of  the 
reviewing  officer. 

While  passing  in  review  or  riding  around  troops  the  staff 
is  formed  in  one  or  more  ranks,  according  to  its  size. 

The  staff,  flag,  and  orderlies  of  brigade  commanders  place 
themselves  in  the  order  prescribed  for  the  staff,  flag,  and 
orderlies  of  the  reviewing  officer. 

When  the  reviewing  officer  is  not  in  front  or  in  rear  of  a 
regiment,  or  other  separate  organization,  its  commander  may 
cause  it  to  stand  at  ease,  to  rest,  or  to  dismount  and  rest,  and  to 
resume  attention  and  mount,  but  so  as  not  to  interfere  with  the 
ceremony. 

When  the  commanding  officer  of  the  troops  turns  out  of  the 
column  his  post  is  on  the  right  of  the  reviewing  officer ;  his 
staff,  in  single  rank,  on  the  right  of  the  staff  already  there;  his 
flag  and  orderlies  in  rear  of  his  staff. 

When  the  column  has  passed,  the  commanding  officer,  with- 
out changing  position,  salutes  the  reviewing  officer  and  then 
with  his  staff  and  orderlies  rejoins  his  command. 

If  the  person  reviewing  the  command  is  not  mounted,  the 
commanding  officer  and  his  staff,  on  turning  out  of  the  column 
after  passing  the  reviewing  officer,  dismount  preparatory  to 
taking  post  on  the  right  of  the  reviewing  officer  and  his 
staff.  In  such  case  the  salute  of  a  commanding  officer,  prior 
to  rejoining  his  command,  is  made  with  the  hand  before  re- 
mounting. 

When  the  general,  the  colonel,  or  the  major  faces  the  line 
to  give  commands,  the  staff  and  orderlies  do  not  change 
position. 

Each  guidon  and,  when  the  rank  of  the  reviewing  officer 
entitles  him  to  the  honor,  each  regimental  standard  salutes  at 
the  command,  HAND  SALUTE;  and  again  in  passing  in  review 
when  6  yards  from  the  reviewing  officer.  The  standard  and 
guidons  are  raised  at  the  command,  TWO,  or  when  they 
have  passed  six  yards  beyond  the  reviewing  officer. 

The  band  of  each  battalion,  corps,  or  regiment  plays  while 
the  reviewing  officer  is  passing  in  front  of  and  in  rear  of  the 
organization. 

During  the  march  in  review  each  band,  immediately  after 
passing  the  reviewing  officer,  turns  out  of  the  column,  takes 


224  MILITARY  SIGNAL  CORPS  MANUAL 

post  in  front  of  and  facing  him,  and  continues  to  play  until 
its  organization  has  passed,  then  ceases  playing  and  follows  in 
rear  of  its  organization;  the  band  of  the  following  organiza- 
tion commences  to  play  as  soon  as  the  preceding  band  has 
ceased.  The  buglers  of  each  organization,  except  those 
pertaining  to  the  organization  commanders,  are  consolidated 
in  rear  of  the  band. 

If  the  band  be  not  present,  the  buglers  of  each  organiza- 
tion, with  the  exceptions  just  noted,  are  consolidated  and 
posted  in  single  rank  in  a  position  corresponding  to  that  of 
the  band.  They  conform  to  what  is  prescribed  for  the  band, 
the  bugler  chief  taking  post  and  performing  the  duties  of 
the  drum  major. 

This  rule  applies  to  all  ceremonies. 

If  the  rank  of  the  reviewing  officer  entitles  him  to  the 
honor,  the  march,  or  flourishes  are  sounded  by  the  field  music  when 
sabers  are  presented,  and  are  sounded  again  in  passing  in  re- 
view at  the  moment  the  standard  salutes,  by  the  musicians 
halted  in  front  of  the  reviewing  officer. 

Buglers  with  the  organization  commanders  do  not  sound  the 
march  or  flourishes. 

The  formation  for  review  may  be  modified  to  suit  the 
ground,  and  the  present  saber  and  the  ride  around  the  line  by 
the  reviewing  officer  may  be  dispensed  with. 

If  the  post  for  the  reviewing  officer  is  on  the  left  of  the 
column  the  troops  march  in  review  with  the  guide  left ;  the 
commanding  officer  and  his  staff  turn  out  of  the  column  to  the 
left,  taking  post  as  prescribed  above,  but  to  the  left  of  the 
reviewing  officer. 

Mounted  companies  of  the  Signal  Corps  pass  in  review  at  a 
walk,  trot,  or  gallop.  When  passing  at  the  trot  or  gallop  no 
salutes  are  made  except  by  the  commander  of  the  troops  when 
he  leaves  the  reviewing  officer. 

When  the  command  is  to  pass  at  an  increased  gait  the 
band  (or  buglers,  if  no  band  is  present)  remains  in  front 
of  the  reviewing  officer  and  continues  to  play  until  the  column 
has  completed  its  second  change  of  direction  after  passing 
the  reviewing  officer.  As  soon  as  the  increased  gait  is  taken  up 
by  the  column  the  band  plays  in  appropriate  time,  ceasing  when 
the  column  has  again  completed  the  second  change  of  direc- 
tion after  passing  the  reviewing  officer.  Upon  the  completion 
of  the  review,  the  band  returns  to  the  position  it  occupied 
before  marching  in  review  or  is  dismissed,  as  may  be  directed. 
If  there  be  more  than  one  band,  the  band  last  in  the  column 
remains  in  front  of  the  reviewing  officer;  the  others  turn  out 


REVIEWS 


225 


REVIEW  OF  FOUR   BATTALIONS  OF   THE  JUNIOR    AMERICAN 
GUARD,  DISMOUNTED 

of  the  column  when  the  increased  gait  is  taken  up  by  their 
respective  organizations,  and  rejoin  them,  or  are  dismissed 
on  the  termination  of  the  review. 

In  reviews  of  brigades  or  larger  commands  each  battalion, 
after  its  rear  has  passed  the  reviewing  officer  50  yards,  takes 
an  increased  gait  for  100  yards  in  order  not  to  interfere  with 
the  march  of  the  column  in  rear. 

The  troops,  having  passed  the  reviewing  officer,  return  to 
their  camps  by  the  most  practicable  route,  being  careful  not 
to  delay  the  march  of  the  troops  in  rear  of  them. 

When  Signal  troops  are  reviewed  in  line  with  Cavalry,  Infantry, 
or  Field  Artillery,  they  are  formed  with  the  leading  men  aligned  on 
the  front  rank  of  the  Infantry  or  on  the  rank  of  Cavalry,  or  on 
the  lead  drivers  of  the  Artillery. 

At  the  command  close  ranks,  march,  with  infantry,  or  attention, 
posts,  with  cavalry  or  field  artillery,  the  Signal  Corps  commander 
commands :  1.  Attention,  2.  POSTS.  The  chiefs  of  platoon 
and  standard  bearers  resume  their  posts  in  line. 

The  instrument,  shop,  and  field  wagons  do  not  accompany 
the  companies  at  the  review  unless  so  ordered. 

When  it  is  necessary  that  an  organization  should  be  reviewed 
before  an  inspector  junior  in  rank  to  the  commanding  officer, 


226  MILITARY  SIGNAL  CORPS  MANUAL 

the    commanding    officer    receives    the    review    and    is    accom- 
panied by  the  inspector,  who  takes  post  on  his  left. 

BATTALION    REVIEW 

The  battalion  being  in  line,  the  major  faces  to  the  front; 
the  reviewing  officer  takes  his  post;  the  major  turns  about 
and  commands :  1.  Prepare  for  review,  2.  MARCH.  The  staff 
remains  in  position,  facing  to  the  front. 

At  the  command  march,  the  chiefs  of  platoons,  and  the  standard 
bearers,  if  present  with  the  standards,  move  up  on  the  line 
of  captains.  Non-commissioned  officers  acting  as  chiefs  of 
platoon  do  not  move  up. 

The  major  then  faces  to  the  front. 

The  reviewing  officer  moves  a  few  yards  toward  the  major 
and   halts ;   the   major   turns    about,   commands :     1.  Hand,    2. 
SALUTE,  and  again  turns  about  and  salutes. 

The  feviewing  officer  returns  the  salute,  the  major  turns 
about,  commands:  TWO,  and  again  turns  to  the  front. 

The  reviewing  officer  approaches  to  within  about  6  yards 
of  the  major,  the  latter  salutes,  returns  saber,  joins  the  re- 
viewing officer,  takes  post  on  his  right,  and  accompanies  him 
around  the  battalion.  The  reviewing  officer  proceeds  to  the 
right  of  the  band,  passes  along  the  front  of  the  officers  to 
the  left  of  the  line,  and  returns  to  the  right,  passing  in  rear 
of  the  line.  The  reviewing  officer  and  those  accompanying 
him  salute  the  standard  when  passing  in  front  of  it. 

While  the  reviewing  officer  is  riding  around  the  battalion 
the  band  plays,  ceasing  when  he  leaves  the  right  to  return  to 
his  post. 

On  arriving  at  the  right  of  the  line  the  major  salutes,  halts, 
and,  when  the  reviewing  officer  and  staff  have  passed,  moves 
directly  to  his  post  in  front  of  the  battalion,  faces  it,  draws 
saber,  and  commands :  1.  Attention,  2.  POSTS.  The  chiefs  of 
platoon  and  standard  bearers  execute  a  left  about  and  take 
their  posts  in  line.  The  major  commands :  1.  By  the  right 
flank;  2.  MARCH;  3.  BATTALION;  4.  HALT.  The  command 
halt  is  given  as  soon  as  the  sections  have  completed  the  turn.  The 
band  takes  post  36  yards  in  front  of  the  leading  company. 

The  column  being  formed,  the  major  commands  :  I.  Pass  in 
review;  2.  Forward;  3.  MARCH.  At  the  command  march  the 
column  marches  off,  the  band  playing.  Without  command  from 
the  major  the  column  changes  direction  at  the  points  indicated, 
and  columns  of  companies  or  platoons  at  full  distance  with 


REril-M'S  227 

guide  to  the  right  is  formed  successively  to  the  left  at  the  sec- 
ond change  of  direction.  The  major  takes  his  post  24  yards 
in  front  of  the  band,  immediately  after  the  second  change. 
The  band,  having  passed  the  reviewing  officer,  turns  to  the  left 
out  of  the  column,  takes  post  in  front  of  and  facing  the  re- 
viewing officer,  and  remains  there  until  the  review  terminates. 

When  the  major  is  6  yards  from  the  reviewing  officer  he 
and  his  staff  salute,  turning  the  head  and  eyes  sharply  to  the 
right.  When  the  major  has  passed  6  yards  beyond  the  review- 
ing officer  he  and  his  staff  resume  the  carry,  turning  the  head 
and  eyes  to  the  front. 

The  other  officers,  non-commissioned  staff  officers  and  the 
drum  major,  salute  at  the  point  prescribed  for  the  major,  turn- 
ing the  head  and  eyes  as  above  described.  Non-commissioned 
officers  and  officers  commanding  platoons  salute  with  the  hand. 

The  reviewing  officer  returns  the  salutes  of  the  major  only 
and  salutes  the  standard. 

The  major,  having  saluted,  takes  post  on  the  right  of  the 
reviewing  officer,  remains  there  until  the  rear  of  the  battalion 
has  passed,  then  salutes  and  rejoins  his  battalion. 

When  the  battalion  arrives  at  its  original  position  in  col- 
umn the  major  commands:  1.  Trot  (or  Gallop);  2.  MARCH. 

The  battalion  passes  in  review  as  before,  except  that  no 
salutes  are  rendered  except  by  the  major  when  he  leaves  the 
reviewing  officer. 

The  review  terminates  when  the  rear  company  has  passed 
the  reviewing  officer;  the  band  then  ceases  to  play  and  rejoins 
the  battalion  or  is  dismissed.  The  major  and  his  staff  rejoin 
the  battalion. 

The  reviewing  officer  may  prescribe  how  often  the  column 
shall  pass  in  review  and  the  gait  or  gaits  to  be  used. 

REVIEW  OF    A    BATTALION  WITH  CLOSED  INTERVALS 

The  battalion  is  formed  in  line,  each  company  being  at 
closed  intervals.  The  review  is  conducted  according  to  the 
principles  previously  explained,  except  that  instead  of  first 
executing  by  the  right  flank  the  battalion  is  formed  in  column 
of  companies  with  closed  intervals,  but  full  distances,  and 
passes  in  review  in  that  formation. 

When  space  is  limited  the  battalion  may  be  formed  in  line 
with  each  company  in  platoon  column.  The  review  will  be 
conducted  on  the  general  principles  previously  explained,  the 
battalion  passing  in  review  either  in  platoon  column  or  in 
column  of  companies  at  full  distance,  as  before. 


INSPECTIONS 

DISMOUNTED  INSPECTIONS 
COMPANY  INSPECTION 

The  company  being  in  line,  dismounted,  the  officers  at  carry 
saber,  the  captain  causes  the  company  to  open  ranks. 

The  captain  then  commands:  PREPARE  FOR  INSPEC- 
TION. 

The  captain  returns  saber,  inspects  the  chiefs  of  platoons 
and  of  sections,  the  ranks,  and  the  file  closers,  beginning  on 
the  right  of  each  and  returning  by  the  left  and  rear.  Each 
man  as  approached  executes  INSPECTION,  PISTOL,  and  after 
being  passed  by  the  inspector  executes  RETURN  PISTOL. 
During  the  inspection  of  the  ranks  the  lieutenants  face  about 
and  stand  at  ease ;  they  may  be  directed  to  accompany  the 
captain  or  to  assist  in  the  inspection.  Upon  the  completion 
of  the  inspection  the  lieutenants  face  to  the  front  and  resume 
the  attention.  The  captain  causes  the  company  to  close  ranks. 

Should  the  inspector  be  other  than  the  captain,  the  latter 
prepares  the  company  for  inspection  and  when  the  inspector 
approaches  brings  the  company  to  attention,  and  from  his  post 
in  front  of  the  right  of  the  company  salutes.  The  salute  ac- 
knowledged, the  captain  carries  saber,  faces  to  the  left,  com- 
mands:  PREPARE  FOR  INSPECTION,  and  again  faces  to  the 
front. 

The  inspection  proceeds  as  before;  the  captain  returns  saber 
and  accompanies  the  inspector  as  soon  as  the  latter  has  in- 
spected him. 

At  inspection  of  quarters  the  inspector  is  accompanied  by 
the  captain  and  followed  by  the  other  officers,  or  by  such  of 
them  as  he  may  designate;  the  men,  without  accouterments, 
stand  uncovered  near  their  respecive  bunks;  in  camp  they 
stand  covered,  without  accouterments,  in  front  of  their  tents ; 
upon  the  approach  of  the  inspector  the  first  sergeant  com- 

228 


INSPECTIONS  229 

mands  ATTENTION,   salutes,  and  leads  the  way  through  the 
quarters  or  camp. 

BATTALION    INSPECTION 

Battalion  inspection  will  be  conducted  in  accordance  with 
the  principles  and  by  the  methods  and  means  laid  down  in 
Company  Inspection,  Dismounted,  and  Battalion  Inspection, 
Mounted. 

MOUNTED  INSPECTIONS 

Organizations  will  be  considered  as  mounted  when  the  ani- 
mal or  motor  transportation  prescribed  as  a  part  of  the 
equipment  of  the  organization  is  present. 

Inspections  will  habitually  be  had  mounted.  Signal  troops 
carry,  for  inspection  mounted,  every  article  that  is  prescribed 
as  a  part  of  the  regular  equipment  and  for  which  there  is  a 
specially  designated  place  on  the  transportation. 

COMPANY    INSPECTION 

The  company  being  in  line  at  normal  intervals,  the  captain 
gives  the  proper  commands  for  forming  the  men  of  the  sec- 
tions in  line  (in  double  rank  in  the  cases  of  outpost  and  tele- 
graph companies)  in  front  of  the  section  transportation. 

He  then  draws  saber  and  commands  :  1.  Prepare  for  inspec- 
tion: 2.  MARCH;  3.  FRONT. 

In  the  cases  of  outpost  and  telegraph  companies  the  sec- 
ond command  is  preceded  by  the  command  Open  ranks. 

At  the  first  command  the  captain  goes  to  the  right  of  the 
company  and  takes  post  facing  to  the  left,  8  yards  in  front  of 
the  guidon ;  and  the  bugler  or  buglers  take  post  2  yards  to 
the  right  of  and  abreast  of  the  guidon. 

At  the  second  command  the  chiefs  of  platoons  move  for- 
ward 8  yards,  and  all  men  dress  to  the  right. 

The  captain  verifies  the  alignment  of  the  chiefs  of  platoons 
of  the  men  in  line  and  of  the  transportation,  returns  to  his 
post  in  front  of  the  guidon  on  line  with  the  chiefs  of  platoons, 
commands  FRONT,  and  faces  to  the  front. 

The  chiefs  of  platoons  cast  their  eyes  to  the  front  as  soon 
as  the  alignment  is  verified. 

As  the  inspector  approaches,  the  men  take  the  position  of 
Inspection  pistol  and  the  buglers  raise  their  bugles  for  in- 
spection. Pistols  are  returned  as  soon  as  inspected. 

The  inspector  begins  the  inspection  by  passing  around  and 


230  MILITARY  SIGXAL  CORPS  MANUAL 

inspecting  the  chiefs  of  platoons,  who,  after  being  inspected, 
face  to  the  rear  and  remain  at  ease  at  their  posts  unless  di- 
rected to  assist  in  the  inspection.  The  inspector  then  goes  to 
the  right  of  the  company  and  inspects  the  buglers  and  guidon, 
after  which  he  inspects  each  section  in  turn,  commencing  at 
the  right  flank,  passing  along  the  front  of  the  section,  and 
returning  in  the  rear  of  the  sections. 

To  inspect  the  company  more  minutely  the  captain  may 
cause  such  men  as  are  mounted  to  dismount,  and,  without 
forming  ranks,  conducts  the  inspection. 

To  inspect  the  technical  signal  equipment  carried  the  cap- 
tain dismounts  all  men,  if  not  already  dismounted,  forms  ranks, 
and  commands  :  1.  Inspection;  2.  Equipment. 

At  this  command  the  horses  of  sections  equipped  with  indi- 
vidual mounts  are  turned  over  to  the  horse  holders,  and  the 
men  fall  in,  in  front  of  their  horses.  The  chiefs  of  sections 
march  the  sections  by  the  right  flank  of  the  sections  to  the 
rear  of  the  transportation,  faces  them  to  the  front,  and  com- 
mands FALL  OUT. 

The  equipment  is  then  removed  from  the  transportation  and 
placed  upon  the  ground  in  such  order  as  may  be  directed. 

When  the  equipment  has  been  laid  out,  the  section  will  form 
in  single  rank  in  rear  of  the  equipment,  facing  to  the  front. 

Upon  the  completion  of  the  inspection  of  a  section  its  equip- 
ment is  replaced  without  command,  and  the  section  is  formed 
and  marched  back  to  its  proper  place,  where  the  men  stand 
at  ease  until  the  completion  of  the  inspection.  All  sections 
when  not  being  inspected  stand  at  ease  awaiting  the  approach 
of  the  inspector,  and  are  brought  to  attention  by  the  chiefs 
of  sections  on  his  approach. 

In  an  animal-equipped  company,  when  the  captain  dis- 
mounts the  mounted  men  in  the  company,  the  guidon  dis- 
mounts with  them  the  chiefs  of  platoons  return  saber,  dis- 
mount, and  stand  to  horse  facing  their  platoons  ;  the  captain 
returns  saber  and  dismounts,  and  his  horse  is  held  by  a  bugler. 
If  the  arms  are  not  to  be  inspected  the  commands  therefor 
are  omitted. 

The  chiefs  of  platoons,  when  the  inspection  of  the  rank 
begins,  face  toward  the  company  and  remain  at  ease,  resum- 
ing front  on  the  completion  of  the  inspection  of  arms,  or  the 
captain  may  require  them  to  assist  him.  If  dismounted,  their 
horses,  if  they  be  so  mounted,  are  held  by  buglers.  The  captain 
may  require  each  chief  to  inspect  his  own  platoon,  while  he 
makes  a  general  inspection. 

While  inspecting  the  company  or  accompanying  the  in- 
spector the  captain  does  not  return  his  saber  while  mounted; 
if  dismounted,  he  returns  saber. 


INSPECTIONS  231 

On  the  completion  of  the  inspection  the  captain  brings 
the  company  to  attention  and  commands  POSTS. 

In  an  animal-equipped  company  the  captain  gives  the  neces- 
sary commands  for  mounting  the  dismounted  men  before  giv- 
ing the  command  POSTS.  The  chiefs  of  platoons  and  the 
buglers  execute  an  about,  resume  their  posts,  and  face  to  the 
front.  The  captain  then  gives  the  necessary  commands  for 
resuming  the  normal  formation. 

Should  the  inspector  be  other  than  the  captain,  the  latter 
prepares  the  company  for  inspection  and  awaits  the  arrival 
of  the  inspector.  Upon  the  approach  of  the  inspector  the  cap- 
tain at  his  post  in  front  of  the  guidon  salutes,  the  inspector 
returns  the  salute  and  informs  him  of  the  character  of  the  in- 
spection desired;  the  captain  gives  the  necessary  commands, 
faces  to  the  front,  and,  when  inspected,  accompanies  the 
inspector. 

BATTALION    INSPECTION 

The  battalion  is  formed  in  column  of  companies,  each  com- 
pany in  line.  On  the  approach  of  the  inspector  the  major  com- 
mands :  1.  Prepare  for  inspection;  2.  MARCH. 

The  companies  are  prepared  for  inspection  as  already 
prescribed. 

The  battalion  staff  officers  place  themselves  in  line  with 
1-yard  intervals  about  30  yards  in  front  of  the  column,  opposite 
the  center,  in  order  of  rank  from  right  to  left ;  the  noncom- 
missioned staff  form  in  a  similar  manner  6  yards  in  rear  of 
the  staff  officers;  the  guard  of  the  standard  marches  to  the 
front  and  takes  post  6  yards  in  rear  of  the  center  of  the  line 
of  the  noncommissioned  staff.  The  major  takes  post  in  front 
of  the  center  of  the  column  6  yards  in  front  of  the  staff. 

Field  and  staff  officers  senior  in  rank  to  the  inspector  do  not 
take  post  in  front  of  the  column,  but  accompany  him. 

The  inspector  inspects  the  major  and,  accompanied  by  the 
latter,  inspects  the  staff  officers. 

The  major  and  his  staff,  as  soon  as  inspected,  return  saber 
and  accompany  the  inspector.  The  noncommissioned  staff 
officers  return  saber  when  inspected. 

The  inspector,  commencing  at  the  head  of  the  column,  in- 
spects the  noncommissioned  staff  and  guard  of  the  standard. 
The  noncommissioned  staff  and  guard  of  the  standard  may 
be  dismissed  as  soon  as  inspected. 

The  captain  of  each  company  not  undergoing  inspection 
dismounts  such  men  as  are  mounted  and  brings  the  men  to 
rest.  As  the  inspector  approaches  the  company  the  captain 
brings  it  to  attention  and,  in  the  case  of  animal-equipped  com- 


232  MILITARY  SIGNAL  CORPS  MANUAL 

panics,  mounts  such  mounted  men  as  are  dismounted;  as  soon 
as  he  himself  has  been  inspected  he  gives  the  necessary  com- 
mands, returns  saber,  and  accompanies  the  inspector.  The 
inspector  proceeds  as  in  company  inspection.  At  its  com- 
pletion the  captain  commands  POSTS,  dismounts  his  mounted 
men,  if  not  already  dismounted;  and  brings  the  company  to 
rest.  Upon  intimation  from  the  inspector  the  major  may  direct 
that  each  company  in  turn  be  dismissed  as  soon  as  inspected. 

The  battalion  may  be  inspected  in  line.  The  inspection 
is  conducted  according  to  the  same  principles  as  when  formed 
in  column.  The  major  and  his  staff  are  inspected  at  their  posts 
in  front  of  the  center  of  the  line;  the  band,  which  remains  at 
its  post  on  the  right,  is  next  inspected;  then  the  companies  in 
order  from  right  to  left. 

If  the  major  is  himself  the  inspector  the  inspection  is  con- 
ducted according  to  the  same  principles. 

INSPECTION    OF    SHELTER-TENT    CAMPS 

To  inspect  an  organization  in  shelter-tent  camp  the  organi- 
ation  is  caused  to  pitch  a  model  camp,  each  man  displaying  his 
equipment  in  front  of  his  shelter  tent,  as  shown  in  the  drawing. 

Men  equipped  as  Infantry  omit  the  individual  mounted 
equipment  shown  and  place  haversack  and  pack  carrier,  where 
saddle  equipment  is  shown.  Haversack  is  placed  on  the  ground 
so  that  lettering  thereon  is  read  from  the  front  and  the  pack 
carrier  is  placed  on  top  of  the  haversack. 

As  soon  as  equipment  is  disposed  men  take  position  1  yard 
in  front  of  the  center  of  their  tent  halves,  facing  the  front, 
and  stand  at  ease.  On  the  approach  of  the  inspector  the  or- 
ganization is  brought  to  attention  and  aligned  by  the  organiza- 
tion commander. 


1.  BLAWRtT.FACK.' 
t.  UNOtRiMUT 

5.  cn AWEHS  . 

4.  SOCKi.TWO  PAins. 
S.IOWtL.MAN-;. 

«.  Houstwirc . 
7. cons. 

6.  TOOTHBPJSH. 
J.TOOTHPAJTt 


O.SOAP.  CAKt. 

I.  H(AT  PAN  a  LIO. 

.  BACON  CAN 

.CONOrUNT  CAN. 

.  CANTtlN . 

.CUP. 

.  KHIfC  . 
.FORK  . 
0.  SPOON. 


KNIft. 

20.  POCKIT  PLItlli- 
I  .  NOSC  BAG   k  HAVtRiAC 


NAILS. 


6.  WUV1.MORM.. 

n  cumrrcoMB. 

IS    G»OOM!NG   CLOTM. 

Z9.  CONTAlNtB.  CANtttN. 


DISPLAY  OF  EQUIPMENT  FOR  INSPECTION. 
233 


FUNERAL  ESCORT 

The  composition  and  strength  of  the  escort  are  prescribed 
in  Army  Regulations. 

The  escort  is  formed  with  its  center  opposite  the  quarters 
of  the  deceased,  the  mounted  men  in  line  to  the  front;  the 
band  (or  musicians)  on  that  flank  of  the  escort  toward  which 
it  is  to  march. 

Upon  the  appearance  of  the  coffin  the  commander  of  the 
escort  commands  :  1.  Hand,  2.  SALUTE,  salutes,  and  the  band 
plays  an  appropriate  air;  the  command:  TWO  is  given,  and  the 
escort  is  formed  in  section  column. 

The  procession  is  formed  in  the  following  order :  1.  Music; 
2.  Escort;  3.  Clergy;  4.  Coffin  and  pallbearers;  5.  Mourners;  6. 
Members  of  the  former  command  of  the  deceased;  7.  Other 
officers  and  enlisted  men;  8.  Distinguished  persons;  9.  Delega- 
tions; 10.  Societies;  11.  Civilians. 

Officers  and  enlisted  men  (Nos.  6  and  7),  with  side  arms,  are 
in  the  order  of  rank,  Seniors  in  front. 

The  escort  marches  at  a  walk  to  solemn  music,  and  on  ar- 
riving at  the  grave  is  formed  in  line  with  the  center  opposite 
the  grave^  the  sections  then  form  line  to  the  front;  the  coffin 
is  carried  along  the  front  of  the  escort  to  the  grave ;  hand 
salute  is  given,  and  the  band  plays  an  appropriate  air ;  the 
coffin  having  been  placed  over  the  grave,  the  music  ceases 
and  hands  are  dropped  to  the  side  at  command. 

After  the  coffin  is  lowered  into  the  grave  and  the  funeral 
services  are  completed,  a  trumpeter  sounds  taps  over  the  grave. 

The  escort  is  then  formed  into  column,  marched  to  the  point 
where  it  was  assembled,  and  dismissed. 

The  band  does  not  play  until  it  has  left  the  inclosure. 

The  funeral  ceremony  for  an  enlisted  man  is  the  same  as 
for  an  officer,  except  that  the  commands  for  saluting  are  omitted; 

234 


ESCORT  235 


the  sergeant  in  command  of  the  escort  salutes  with  the  hand  on  the 
apnearance  of  the  coffin  at  the  quarters  of  the  deceased  and  also 
when  the  coffin  is  carried  along  the  front  of  the  escort  to  the  grave. 

When  the  distance  to  the  place  of  interment  is  considerabte, 
the  escort  after  leaving  the  camp  or  garrison  may  march  at 
ease  until  it  approaches  the  burial  ground,  when  it  is  brought 
to  attention.  The  music  does  not  play  while  marching  at  ease. 

In  marching  at  attention  the  field  music  may  alternate  with 
the  band  in  playing. 

When  it  is  impracticable  for  transportation  to  approach 
the  grave,  it  is  left  outside  the  inclosure.  If  the  escort 
consists  of  Signal  Corps  only,  the  officers,  non-commissioned 
staff  officers,  and  all  individually  mounted  men  dismount, 
turn  over  their  horses  to  the  horse  holders,  and  the 
officers  draw  saber;  a  suitable  formation  is  then  taken  and 
the  coffin  is  escorted  to  the  grave,  where  line  is  formed  and  the 
same  ceremonies  are  performed  as  before  prescribed.  The 
ceremony  at  the  grave  having  been  completed,  the  command 
remains  in  line  until  the  bugler  sounds  taps  over  the  grave. 

Should  the  entrance  to  the  cemetery  prevent  the  hearse  ac- 
companying the  escort  till  the  latter  halts  at  the  grave,  the 
column  is  halted  at  the  entrance  long  enough  to  take  the 
coffin  from  the  hearse,  when  the  column  is  again  put  in  march. 
The  Cavalry,  Artillery,  and  Signal  Corps  of  the  escort,  when 
unable  to  enter  the  inclosure,  turn  out  of  the  column  and 
salute  the  coffin  as  it  passes. 

In  all  funeral  ceremonies  six  pallbearers  will  be  selected  as 
far  as  practicable  from  the  grade  of  the  deceased.  If  the  de- 
ceased is  a  commissioned  officer,  the  coffin  is  borne  by  six 
commissioned  officers;  if  a  non-commissioned  officer  or  private, 
by  six  privates. 

When  arms  are  presented  at  the  funeral  of  a  general  officer, 
the  trumpeters  sound  the  march  or  flourishes,  according  to  the 
rank  of  the  deceased,  after  which  the  band  plays  an  appropriate 
air. 

At  the  funeral  of  a  mounted  officer  or  enlisted  man,  his 
horse,  in  mourning  caparison,  follows  the  hearse. 

When  necessary  to  escort  the  remains  from  the  quarters 
of  the  deceased  to  the  church  before  the  funeral  service,  arms 
are  presented  upon  receiving  the  remains  at  the  quarters  and 
also  as  they  are  borne  into  the  church. 

Before  the  funeral  the  commander  of  the  escort  gives  the 
clergyman  and  pallbearers  all  needed  directions. 


THE  STANDARD 

Whenever  in  these  regulations  the  term  the  standard  is  used  it 
includes  Tx>th  the  national  and  the  battalion  standards ;  if  either 
alone  is  to  be  referred  to,  the  term  the  national  standard  or  the 
battalion  standard  is  used. 

The  manual  of  the  standard  is  as  prescribed  for  the  guidon 
except  that  at  carry  standard,  dismounted,  the  ferrule  of  the  lance 
is  supported  at  the  right  hip. 

The  standard  salutes  an  officer  entitled  to  the  honor,  but  in  no 
other  case. 

The  guard  of  the  standard. — The  guard  of  the  standard  con- 
sists of  the  color  sergeants  and  of  two  experienced  men  selected 
by  the  commanding  officer.  The  guard  is  habitually  formed  in  line, 
the  color  sergeants  in  the  center. 

The  national  standard  is  carried  by  the  senior  color  sergeant, 
who  is  nearest  to  the  right  flank  of  the  guard  and  who  commands 
the  guard.  The  Signal  Corps  standard  is  carried  by  the  other  color 
sergeant.  The  latter  conforms  to  the  movements  of  the  former, 
maintaining  his  position  on  the  left. 

The  standard,  kept  at  the  quarters  or  office  of  the  commanding 
officer,  is  escorted  by  the  guard  to  the  place  of  formation  of  the 
battalion  and  is  similarly  returned. 

Post  of  the  standard. — At  the  formation  of  the  battalion,  as 
soon  as  the  companies  have  taken  their  places,  the  guard  of  the 
standard  takes  post  midway  between  the  two  center  companies  in 
line  abreast  of  the  front  ranks  of  the  sections ;  in  column,  at  the 
center  of  the  column. 

If  the  formation  of  the  battalion  is  changed  from  line  to  column 
or  the  reverse,  the  standard  conforms  to  the  movement,  taking 
its  new  position  by  the  most  direct  route. 

When  during  exercises  the  battalion  formation  is  broken  up, 
the  standard  joins  the  commanding  officer  or  is  dismissed,  as  may 
be  directed  by  the  adjutant. 

236 


MANUAL  OF  THE  GUIDON  237 

THE    GUIDON 

The  position   of  carry  guidon,   dismounted. — The   lance   of  the 

guidon  is  held  vertically  in  the  right  hand,  thumb  in  front  of  the 

lance,   forefinger  along  the  side,   ferrule  about  6  inches   from  the 
ground.    It  is  thus  carried  in  marching. 

When  leading  the  horse  the  lance  is  held  in  a  corresponding 
position  in  the  left  hand. 

The  position  of  order  guidon. — The  ferrule  of  the  lance  rests 
on  the  ground  on  a  line  with  and  touching  the  toe  of  the  right  shoe ; 
the  right  hand  grasps  the  lance  in  the  same  manner  as  when  at  carry. 

The  position  of  parade  rest. — The  ferrule  of  the  lance  is  on 
the  ground  as  at  the  order ;  the  lance  is  held  with  both  hands  in 
front  of  the  body,  left  hand  uppermost. 

To  mount  and  dismount — The  position  of  carry  guidon,  mounted. 
— At  stand  to  horse  the  ferrule  of  the  lance  rests  on  the  ground  on 
a  line  with  and  touching  the  toe  of  the  left  shoe,  lance  vertical  and 
supported  by  the  left  hand ;  hand  at  the  height  of  the  neck,  elbow 
and  forearm  closed  against  the  lance. 

Preparatory  to  mounting,  grasp  the  reins  and  a  lock  of  the 
mane  in  the  left  hand,  lance  held  in  the  same  hand,  reins  on  the 
near  side  of  the  lance ;  place  the  right  hand  on  the  pommel  and 
mount  in  the  usual  manner.  After  mounting,  grasp  the  lance  with 
the  right  hand  under  the  left,  which  lets  go  of  it  without  quitting 
the  reins ;  carry  the  lance  to  the  right  side,  lower  and  place  the 
ferrule  in  the  stirrup  socket.  The  right  hand  then  grasps  the 
lance,  forearm  nearly  horizontal,  the  arms  through  the  sling,  lance 
vertical;  this  is  the  position  of  carry  guidon,  mounted. 

Dismounting  with  the  guidon  is  executed  in  a  manner  the  re- 
verse of  the  foregoing. 

(Note. — Mounting  and  dismounting  with  the  wire  pike  should 
be  similarly  executed.) 

Salutes — Being  mounted. — Lower  the  guidon  to  the  front  until 
the  lance  (under  the  right  arm)  is  horizontal. 

Being  dismounted.— Slip  the  right  hand  up  the  lance  as  high  as 
the  eye,  then  lower  the  lance  to  the  front  by  straightening  the  right 
arm  to  its  full  extent. 

If  marching,  the  salute  is  executed  when  at  6  yards  from  the 
officer  entitled  to  the  salute;  the  carry  is  resumed  after  passing  6 
yards  beyond  him. 

At  the  halt  the  salute  is  executed  at  the  command:  1.  Hand, 
2.  SALUTE.  The  carrv  is  resumed  at  the  command  TWO. 


MANUAL  OF  THE  SABER 

1.  Draw,  2.  SABER. 

At  the  command  draw,  unhook  the  saber  with  the  thumb 
and  first  two  fingers  of  the  left  hand,  thumb  on  the  end  of  the 
hook,  fingers  lifting  the  upper  ring;  grasp  the  scabbard  with 
the  left  hand  at  the  upper  band,  bring  the  hilt  a  little  forward, 
seize  the  grip  with  the  right  hand,  and  draw  the  blade  6  inches 
out  of  the  scabbard,  pressing  the  scabbard  against  the  thigh 
with  the  left  hand. 

At  the  command  Saber,  draw  the  saber  quickly,  raising 
the  arm  to  its  full  extent  to  the  right  front,  at  an  angle  of  about 
45  deg.  with  the  horizontal,  the  saber,  edge  down,  in  a  straight  line 
with  the  arm;  make  a  slight  pause  and  bring  the  back  of  the 
blade  against  the  shoulder,  edge  to  the  front,  arm  nearly  ex- 
tended, hand  by  the  side,  elbow  back,  third  and  fourth  fingers 
back  of  the  grip;  at  the  same  time  hook  up  the  scabbard  with 


THE    EXECUTION    OF    THE    COMMAND: 
1st  Position  2nd  Position 


DRAW    SABER 

3rd  Position 


238 


MANUAL  OF  THE  SABER  239 

the  thumb  and  first  two  fingers  of  the  left  hand,  thumb  through 
the  upper  ring,  fingers  supporting  it;  drop  the  left  hand  by  the 
side. 

This  is  the  position  of  carry  saber  dismounted. 

Officers  and  non-commissioned  officers  armed  with  the  saber 
unhook  the  scabbard  before  mounting;  when  mounted,  in  the 
first  motion  of  "draw  saber"  they  reach  with  the  right  hand 
over  the  bridle  hand  and  without  the  aid  of  the  bridle  hand 
draw  the  saber  as  before ;  the  right  hand  at  the  "carry"  rests 
on  the  right  thigh. 

On  foot  the  scabbard  is  carried  hooked  up. 

When  publishing  orders,  calling  the  roll,  etc.,  the  saber  is 
held  suspended  from  the  right  wrist  by  the  saber  knot;  when 
the  saber  knot  is  used  it  is  placed  on  the  wrist  before  drawing 
saber  and  taken  off  after  returning  saber. 


1st   POSITION  OF:   PRESENT  SABER   (or  ARMS) 
Being   at   the    order    or    carry:      1.   Present.   2.    SABER    (or 
ARMS). 

At  the  command  "present"  raise  and  carry  the  saber  to  the 
front,  base  of  the  hilt  as  high  as  the  chin  an'd  6  inches  in  front 
of  the  neck,  edge  to  the  left,  point  6  inches  farther  to  the  front 
than  the  hilt,  thumb  extended  on  the  left  of  the  grip,  all  fingers 
grasping  the  grip. 

At  the  command  "saber,"  or  "arms,"  lower  the  saber  point 
in  prolongation  of  the  right  foot  and  near  the  ground,  edge 
to  the  left,  hand  by  the  side,  thumb  on  left  of  grip,  arm  ex- 
tended. If  mounted,  the  hand  is  held  behind  the  thigh,  point 
a  little  to  the  right  and  front  of  the  stirrup. 


240 


MILITARY  SIGNAL  CORPS  MANUAL 


In  rendering  honors  with  troops  officers  execute  the  first 
motion  of  the  salute  at  the  command  "present",  the  second 
motion  at  the  command  "arms";  enlisted  men  with  the  saber 
execute  the  first  motion  at  the  command  "arms"  and  omit  the 
second  motion. 

Being  at  a  carry :    1.  Order,  2.  SABER  (or  Arms). 

Drop  the  point  of  the  saber  directly  to  the  front,  point  on 
or  near  the  ground,  edge  down,  thumb  on  back  of  grip. 

Being  at  the  "present  saber,"  should  the  next  command  be 
"order  arms,"  officers  and  noncommissioned  officers  armed  with 
the  saber  "order  saber;"  if  the  command  be  other  than  "order 
arms,"  they  execute  "carry  saber." 

When  arms  are  brought  to  the  order  the  officers  or  enlisted 
men  with  the  saber  drawn  "order  saber." 


Order  Saber 


Parade  Rest 


Carry  at  Double  Time 


The  saber  is  held  at  the  carry  only  while  giving  commands, 
marching  at  attention,  or  changing  position  in  quick  time. 

When  at  the  order,  sabers  are  brought  to  the  carry  when 
arms  are  brought  to  any  position  except  the  "present"  or 
"parade  rest." 

Being  at  the  order:     1.  Parade,  2.  REST. 

Take  the  position  of  parade  rest  except  that  the  left  hand 
is  uppermost  and  rests  on  the  right  hand,  point  of  saber  on  or 
near  the  ground  in  front  of  the  center  of  the  body,  edge  to  the 
right. 

At  the  command  "attention"  resume  the  order  saber  and  the 
position  of  the  soldier. 

In  marching  in  double  time  the  saber  is  carried  diagonally 
across  the  breast,  edge  to  the  front;  the  left  hand  steadies 
the  scabbard. 


MANUAL  Ol-   THE  SABER 


241 


Officers  and  noncommissioned  officers  armed  with  the  saber, 
on  all  duties  under  arms  draw  and  return  saber  without  wait- 
ing for  command.  All  commands  to  seldiers  under  arms  are 
given  with  the  saber  drawn. 

Being  at  a  carry:    1.  Return,  2.  SABER. 

At  the  command  "return"  carry  the  right  hand  opposite 
to  and  6  inches  from  the  left  shoulder,  saber  vertical,  edge  to 
the  left;  at  the  same  time  unhook  and  lower  the  scabbard  with 
the  left  hand  and  grasp  it  at  the  upper  hand. 

At  the  command  "saber"  drop  the  point  to  the  rear  and  pass 
the  blade  across  and  along  the  left  arm;  turn  the  head  slightly 


1st  POSITION:    RETURN  SABER 

to  the  left,  fixing  the  eyes  on  the  opening  of  the  scabbard, 
raise  the  right  hand,  insert  and  return  the  blada;  free  the 
wrist  from  the  saber  knot  (if  inserted  in  it),  turn  the  head  to 
the  front,  drop  the  right  hand  by  the  side;  hook  up  the  scab- 
bard with  the  left  hand,  drop  the  left  hand  by  the  side. 

Officers  and  noncommissioned  officers  armed  with  the  saber, 
when  mounted,  return  saber  without  using  the  left  hand;  the 
scabbard  is  hooked  up  on  dismounting. 

At  inspection  enlisted  men  with  the  saber  drawn  execute 
the  first  motion  of  "present  saber"  and  turn  the  wrist  to  show 
both  sides  of  the  blade,  resuming  the  carry  when  the  inspector 
has  passed. 


PART  III— TECHNICAL  INSTRUCTION  AND  APPARATUS 
TELEGRAPHY  AND  TELEPHONY 

THE  VOLTAIC   CELL,   OHM'S   LAW  AND   PRIMARY   AND 
SECONDARY   BATTERIES 

THE  VOLTAIC  CELL 

If  zinc  and  carbon  are  immersed  in  an  acid  or  saline  solution  and 
the  two  connected  externally  by  a  wire,  an  electric  current  will  flow 
from  one  to  the  other.  Any  two  dissimilar  metals  when  immersed 
in  an  acid  solution  which  acts  on  one  more  than  on  the  other  and 
connected  externally  by  a  wire  will  produce  results.  There  are  a 
few  non-metallic  substances  which  if  used  in  a  voltaic  cell  in  the 
place  of  metal  elements  will  produce  the  same  result.  The  sub- 
merged substances  are  termed  plates  or  elements,  and  the  solution 
is  termed  electrolyte.  The  combination  of  plates  or  elements,  elec- 
trolyte, and  containing  vessel  constitutes  a  voltaic  cell. 

Authorities  differ  as  to  just  why  a  current  of  electricity  flows 
under  the  conditions  just  stated.  Suffice  it  to  say  that  it  does  flow, 
and  that  invariably  one  of  the  plates  is  acted  upon  (decomposed  or 
eaten  away)  to  a  very  much  greater  degree  than  the  other.  Ex- 
periment has  shown  that  under  the  before-mentioned  conditions  sub- 
stances which  are  acted  upon  equally  do  not  cause  a  current  of 
electricity  to  flow. 

Where  carbon  and  zinc  are  used  as  the  plates  in  the  voltaic  cell, 
the  carbon  is  termed  the  negative  plate  or  element  and  the  zinc 
is  termed  the  positive  plate  or  element.  The  carbon  or  negative 
element  forms  the  positive  pole  of  the  battery,  and  the  zinc  or 
positive  element  forms  the  negative  pole.  The  reason  for  this  ap- 
parent contradiction  is  as  follows :  In  any  source  of  electricity  the 
current  flows  from  positive  to  negative,  and  in  the  voltaic  cell,  with 
plates  connected  externally  with  a  wire,  the  current  flows  from 
zinc  through  electrolyte  to  carbon ;  this  is  termed  the  internal  circuit. 
Outside  the  battery  current  flows  from  carbon  plate  through  wire  to 
zinc ;  this  is  termed  the  external  circuit,  thus  it  will  be  noted  that 

242 


TELEGkAl'llY  AND    TELEl'HONY 


243 


in  the  internal  circuit  the  current  flows  to  and  from  directly  opposite 
plates  to  those  in  the  external  circuit.    Figure  1  illustrates  this. 

The  term  "circuit"  is  applied  to  the  entire  path  through  which 
the  current  of  electricity  flows.  The  wire  joining  the  plates  is  a 
conductor.  Bringing  the  ends  of  the  conductor  into  contact  is 
called  making  or  closing  the  circuit,  and  their  separation,  opening  or 
breaking  the  circuit.  A  substance  through  which  the  current  readily 
flows  is  a  conductor.  Any  substance  which  offers  an  extremely  high 
resistance  to  the  flow  of  an  electric  current  is  an  insulator.  Most 


FIG.   l-VOLTAIC    CELL 

metals  are  good  conductors,  while  mica,  glass,  porcelain,  dry  wood, 
dry  atmosphere,  rubber,  etc.,  are  insulators. 

OHM'S  LAW 

With  any  circuit  through  which  a  direct  current  of  electricity 
is  flowing  there  are  the  three  governing  factors  which  follow : 
(1)  The  difference  of  potential  between  the  positive  and  nega- 
tive pole  of  the  generating  medium,  known  as  the  pressure  or 
electro-motive  force,  the  unit  of  which  is  the  volt.  (Abbreviated 
V.,  E.,  or  E.M.F.)  One  volt  is  that  electro-motive  force  which 
would  maintain,  in  a  circuit  having  1  ohm  resistance,  a  current 
strength  of  1  ampere. 

(2)  The  resistance  or  opposition  by  the  conductor  to  the  flow 
of  current,  the  unit  of  which  is  the  ohm.  (Abbreviated  R.)  One 
ohm  is  that  resistance  in  a  circuit  which,  if  impressed  with  an  electro- 
motive force  of  1  volt,  allows  a  current  strength  of  1  ampere  to 
flow  through  the  circuit.  One  ohm  is  the  resistance  of  a  column  of 


244  MILITARY  SIGNAL  CORPS  tt'ANl  .  //. 

mercury  about  42  inches  high  and  0.00155  square  inch  in  cross-sec- 
tional area  at  zero  centigrade. 

(3)  The  current  strength  or  rate  of  flow,  the  unit  of  which  is 
the  ampere.  (Abbreviated  I.)  One  ampere  is  that  strength  of  cur- 
rent which  would  be  maintained  in  a  circuit  having  1  ohm  resistance 
if  impressed  with  an  electromotive  force  of  1  volt. 

From  the  foregoing  it  will  be  noted  that  a  definite  relation  exists 
between  these  factors,  so  that  the  value  of  any  one  of  them  can 
be  found  if  the  values  of  the  other  two  are  known.  This  relation, 
expressed  by  Ohm's  law,  is  as  follows : 

(a)  The  current  strength  in  a  circuit  may  be  found  by  dividing 
the  pressure,  or  electromotive  force,  applied  to  it  by  the  resistance. 

E  M  F  (in  volts) 
I   (in  amperes)  —  • 

R  (in  ohms) 

(b)  The  electromotive  force,  or  pressure,  required  to  maintain 
a  certain  current  strength  in  a  circuit  may  be  found  by  multiplying 
the  current  in  amperes  by  the  resistance  in  ohms. 

(c)  The  resistance  in  any  circuit  may  be  found  by  dividing  the 
electromotive  force  by  the  current  strength. 

E  M'F   (in  volts) 

R   (in  ohms)  = — 

I   (in  amperes) 

When  the  total  electromotive  force  is  used  in  Ohm's  law,  the 
total  resistance  must  be  used  to  calculate  the  current  strength.  For 
example,  if  a  coil  of  0.5  ohm  resistance  is  connected  to  a  cell  of  2 
volts  E.M.F.,  the  current  through  the  coil  would  not  be 

(E^R)  or  (2-H).5)=4 

amperes  as  might  be  supposed.  It  requires  a  certain  part  of  the  cell's 
E.M.F.  to  force  the  current  through  the  internal  circuit;  therefore, 
the  internal  and  external  resistances  must  always  be  added  together 
and  divided  into  the  total  E.M.F.  to  find  the  current  flowing.  Now, 
if  the  internal  resistance  of  the  cell  were  0.5  ohm,  the  total  resist- 
ance would  be  0.5  +  0.5  =  1  ohm  and 

I=(E-f-R)=(2-H)=2    amperes,  or  half 
of  the  first  result. 

Ohm's  law  applies  also  to  any  part  of  a  circuit  the  same  as  to 
the  whole  circuit.  When  applied  to  part  of  a  circuit  care  must  be 
taken  to  use  only  the  E.M.F.,  resistance,  and  current  strength  of  that 
portion  of  a  circuit  considered.  Therefore,  when  E  is  used  as  total 
E.M.F.,  R  must  be  the  total  resistance,  and  when  E  is  used  as  the 
pressure  applied  to  part  o-f  a  circuit,  R  to  correspond  must  be  the 


TELEGRAPHY  AND  TELEPHONY  245 

resistance  of  that  part  of  the  circuit  to  which  the  E  was  applied. 
This  application  of  the  law  may  be  illustrated  by  the  following 
problem : 

The  E.M.F.  of  a  cell  is  2  volts;  its  internal  resistance  0.5  ohm. 
It  is  connected  to  three  spools  of  wire  in  series.  By  measurement 
we  find  that  the  E  causing  the  current  to  flow  through  one  of  the 
spools,  of  which  the  R  =  0.4  ohm,  is  0.6  volt.  What  current  is  flow- 
ing through  this  spool? 

E     °-6 
By  Ohm's  law  I~  =  Q-^  =  1.5  amperes. 

Now,  since  the  current  is  the  same  in  all  parts  of  a  series  circuit, 
1.5  amperes  flow  through  each  of  the  spools  and  also  through  the 
internal  resistance.  This  also  illustrates  the  difference  between  the 
E.M.F.  and  potential  difference.  The  difference  of  potential  or 
pressure  between  the  ends  of  the  spool  is  0.6  volt,  while  the  E.M.F. 
of  the  cell  is  2  volts. 

What  part  of  the  total  E.M.F.  is  used  in  overcoming  the  internal 
resistance  of  the  cell  in  the  above  problem? 
By  Ohm's  law  E  =  I  X  R  =  1.5  X  0.5  =  0.75  volt. 
This  gives  pressure  lost  or  "volts  drop"  inside  the  cell. 
The  resistance  of  any  conductor  increases   with   its  length  and 
decreases  with  area  of  cross  section  and  for  most  conductors  the 
esistance  increases  with  rise  of  temperature. 

Electric  current  so  far  discussed  has  been  direct  or  undirectional 
s  appertaining  to  its  flow  in  a  circuit  and  is  termed  "direct  current." 
(Abbreviated  D.C.)  This  current  may  be  so  treated  that  it  will 
become  either  alternating  or  pulsating  in  character.  When  this  oc- 
curs Ohm's  law  still  applies,  but  there  are  other  factors  that  must 
be  considered  in  computing  values  of  I.,  E.M.F.,  or  R. 

With  an  alternating  current  (abbreviated  A.C.)  the  flow  in  a 
circuit  is  continually  reversing  in  direction.  Certain  types  of  gen- 
erators produce  alternating  currents  which  change  direction  periodi- 
cally and  uniformly,  the  speed  of  rotation  of  the  rotor  of  such 
generators  being  constant.  Such  currents  are  expressed  in  number 
of  cycles  per  second,  60  cycles  being  the  most  commonly  used  for 
commercial  electric  lighting  and  power  systems.  Two  alternations 
hange  of  direction)  are  contained  in  a  cycle. 

Unlike  this  current,  the  alternating  current  produced  in  telephonic 
communication  is  not  periodically  uniform  nor  is  the  E.M.F.  in  any 
way  constant.  The  E.M.F.  of  these  alternating  currents  is  usually 
extremely  high  and  the  current  strength  very  low,  consequently  the 
source  of  the  current  for  transmitting  the  voice  waves  from  a 
single  instrument  need  only  be  capable  of  producing  a  comparatively 


246  MILITARY  SIGNAL  CORPS  MAX  UAL 

weak  current  strength.  For  this  reason  a  person  coming  into  con- 
tact with  both  sides  of  a  talking  circuit  will  not  be  injured  by  the 
talking  current. 

A  pulsating  current  is  one  which  varies  in  magnitude.  As  ordinari- 
!y  employed  the  term  refers  to  undirectional  current.  A  pulsating 
current  may  also  be  formed  by  superimposing  upon  a  direct  cur- 
rent an  alternating  current.  When  the  alternating  current  is  flowing 
in  the  same  direction  as  the  direct  current  the  former  accentuates 
th»  latter,  and  when  flowing  the  reverse  direction  it  counteracts,  in  a 
degree,  the  direct  current.  These  currents  will  be  encountered  in  the 
study  of  the  operation  of  the  telephone  and  similar  apparatus. 

STANDARD   BATTERIES    SUPPLIED   BY   THE    SIGNAL   CORPS 

There  are  two  classes  of  batteries,  viz.,  primary  and  secondary, 
the  latter  sometimes  being  known  as  storage  batteries  or  accumu- 
lators. 

Primary  batteries  are  divided  into  two  classes,  known  as  open- 
circuit  and  closed-circuit,  and  while  there  is  a  great  variety  of  each 
class,  the  basic  principle  employed  is  the  same. 

Open-circuit  cells  are  used  for  intermittent  service  where  current 
is  required  for  only  short  intervals  of  time,  such  as  in  operating 
electric  bells.  Open-circuit  cells  kept  in  continuous  service  for  some 
time  become  polarized  or  completely  exhausted,  but  will  recuperate 
to  a  considerable  degree  on  open  circuit.  The  dry-battery  is  an 
excellent  example  of  the  open-circuit  type. 

Closed-circuit  cells  are  adapted  for  supplying  current  continuous- 
ly until  the  energy  of  the  chemical  is  nearly  expended.  This  is 
the  form  of  primary  cell  most  extensively  used  in  telegraphy,  where 
a  small  but  constant  current  is  required. 

While  formerly  the  Signal  Corps  issued  several  different  kinds 
of  open-circuit  primary  battery  cells,  such  as  the  Laclanche,  Gonda, 
and  the  Sampson,  all  of  which  employed  carbon  and  zinc  for  ele- 
ments, sal-ammoniac  dissolved  in  water  as  electrolyte  and  a  contain- 
ing jar  of  glass,  experience  has  shown  that  the  dry-cell  type  of  pri- 
mary battery  is  most  satisfactory,  and  consequently  this  type  forms 
the  standard  issue  of  the  Signal  Corps. 

While  all  dry  cells  of  this  type  conform  in  general  with  the 
following  description,  it  is  found  that  different  makes  vary  in 
efficiency.  In  order  to  ascertain  the  comparative  merits  of  each  make, 
a  careful  life  test  is  periodically  made  in  the  Signal  Corps  labora- 
tory, Washington,  D.  C. 

The  dry  battery  is  a  form  of  sal-ammoniac  battery  in  which  the 
zinc  plate  constitutes  both  the  containing  vessel  and  negative  pole, 
thereby  doing  away  with  the  breakable  glass  jar.  An  absorbent 
porous  material  with  a  deplorarizing  mixture  around  it  fills  the 


TELEGRAPHY  AND  TELEPHONY 


247 


space  between  the  carbon  in  the  center  and  the  zinc  vessel.  This 
porous  material  is  saturated  with  a  solution  containing  chloride  of 
zinc  and  sal-ammoniac.  The  top  of  the  cell  is  sealed  with  asphalt 
or  similar  material.  Binding  posts  for  zinc  and  carbon  elements, 
and  pasteboard  cover  to  prevent  short  circuiting  with  adjacent 
cells,  complete  this  form  of  battery.  These  cells  when  carefully 
manufactured  and  properly  stored  are  reliable.  The  cell  can  not 
be  renewed,  but  their  low  cost  and  the  convenience  afforded  by 
nature  of  the  construction  makes  them  superior  to  the  wet  cell 
f  r  general  use. 

When  these  cells  are  exhausted,  a  short  period  of  usefulness  may 
be  obtained  from  them  in  the  following  manner :     Punch  a  number 


No  6  Ntx4 

FIG.  2.-DRY  CELL  BATTERIES  OF  STANDARD  SIZES 
of  holes  through  the  zinc  containing  case  and  place  them  in  jars 
containing  a  solution  of  sal-ammoniac  and  water.  Salt  solution 
for  this  purpose  may  be  used,  but  it  is  not  as  effective  as  the  sal- 
ammoniac.  The  standard  sizes  of  the  dry  cell  are  shown  in 
figure  2,  but  only  two  of  these  sizes  are  in  general  use  with  post 
telephone  systems  and  with  instruments  used  in  the  field.  Size  No. 
6,  figure  2,  is  invariably  used  when  a  local  battery  is  desired  for 
telephones  of  post  telephone  systems. 

The  tungsten  type  A  battery  shown  in  figure  2  is  used  with  the 
service  buzzer,  the  1914  induction  telegraph  set,  the  camp  telephone 
ra-io  test  buzzer,  and  the  hand  flashlight.  This  type  of  battery  is 


248 


MILITARY  SIGNAL  CORPS  MANUAL 


similar  in  construction  to  that  first  described,  but  in  order  to 
obtain  a  comparatively  high  voltage  with  minimum  weight  and 
bulk,  the  cells  are  of  small  diameter  and  two  cells  r.re  so  placed  in  a 
rigid  paper  tube  that  they  are  connected  in  series.  This  combination 
gives  a  total  voltage  of  3 — ll/2  being  normal  voltage  of  each  cell. 

RESERVE  TYPE   DRY   CELL 

The  ordinary  type  of  dry  cell  deteriorates  if  kept  long  in  storage, 
even  though  not  in  use.  To  provide  a  type  of  dry  cell  which  could 
be  kept  in  storage  without  deterioration,  the  Signal  Corps  issues 
a  dry  cell  known  as  the  "reserve  type,"  shown  in  figure  3.  This 


.    No.e  . 

RESERVE 
Dimensions  an  of  cdb 


-No.4-0 

-RCSCRVt- 
paper  coxenny  removed. 


FIG.  3.-RESERVE  DRY  CELL  BATTERIES,  STANDARD  SIZES 

cell,  although  containing  all  the  elements  and  ingredients  of  an  or- 
dinary dry  cell,  does  not  become  active  until  water  has  been  poured 
into  a  cavity  of  the  carbon  element.  To  place  the  cell  in  service, 
remove  the  plug  from  the  top  of  the  carbon  element  and  fill  with 
water  (rain  water  preferred).  As  soon  as  this  is  absorbed,  fill 
again,  until  the  following  amounts  of  water  have  been  added  : 
Type  4-0,  154  ounces;  type  5,  2l/2  ounces;  type  6,  Zl/2  ounces;  after 
which  no  more  water  should  be  added  to  these  dry  batteries. 

Great  care  should  be  exercised  in  pouring  the  water,  in  order  to 
avoid  wetting  the  cardboard  cover.     If  no  funnel  is  available  it  is 


TELEGRAPHY  AND  TELEPHONY 


249 


advisable  to  remove  cardboard  container  during  filling.  When  the 
cell  becomes  weak  through  use,  a  little  sal-ammoniac  solution 
placed  inside  the  carbon  element  will  rejuvenate  it  to  some  extent. 

Referring  to  figures  2  and  3,  it  will  be  noted  that  the  two 
sizes  of  reserve  dry  cells  correspond  in  dimensions  with  cells  of 
similar  number  not  of  the  reserve  type.  The  reserve  type  has  prac- 
tically been  adopted  by  the  Signal  Corps.  The  No.  5  size  is  not  a 
standard  issue. 

The  voltage  of  a  cell  is  important  and  should  in  no  case  be  less 
than  one  volt,  but  the  internal  resistance  is  of  greater  importance 
since  the  cell  which  is  nearly  exhausted  may  at  times  show  a  com- 
paratively high  E.M.F. 

With  an  ammeter  connected  directly  to  the  terminals  of  a 
No.  6  cell,  new  cells  should  show  a  reading  of  at  least  15  amperes 
(some  cells  will  show  24).  The  voltage  reading  of  a  new  cell  on 
open  circuit  shoud  be  at  least  1.4.  Ammeter  readings  should  be 
accomplished  as  quickly  as  possible,  as  in  making  the  test  the  cell 
is  practically  short  circuited,  the  ohmic  resistance  of  an  ammeter 
being  very  low. 

Ordinarily,  dry  cells  which  when  tested  show  a  voltage  lower 
than  1  or  a  reading  of  ammeter  less  than  2  should  under  no  cir- 
cumstances be  turned  into  supply  depots  or  transferred  to  ac- 
countable officers.  This  does  not  apply  to  the  reserve  type  of  cell 
unless  it  has  been  put  in  commission  by  the  addition  of  water. 

Dry  cells  in  good  condition  have  a  voltage  of  about  1.45.    The  inter- 
nal resistance  and  weights  of  the  various  types  are  about  as  follows  : 


Size 

Internal 
resistance 

Weight 

Size 

Internal 
resistance 

Weight 

4-0   

Ohms 
0  25 

Ounces 
\\u 

g 

Ohms 
0  jo 

Ounces 
on 

4    

.25 

9 

Reserve    4-0... 

.29 

HVi 

5    

.20 

18 

Reserve    5  

.22 

18 

6    

.20 

32 

Reserve    6  

.19 

32 

7    

.12 

56 

Type    A 

tungsten1..  . 

.30 

8 

1  Internal  resistance  shown  is  for  each  cell  of  the  unit.  Weight  shown  is 
for  the  unit  complete,  includng  cardboard  container. 

CLOSED-CIRCUIT    BATTERIES 

The  gravity,  Fuller,  and  Edison  are  the  types  of  closed-circuit 
cells  supplied  by  the  Signal  Corps.  Useful  data  on  these  cells  is 
shown  in  the  following  table : 


Type  of  Cell 

Voltage 

Weight 

Internal 
Resistance 

Gravity  .       

1.00 

Pounds 

1134 

Ohms 

30 

Fuller                              

2.00 

12 

2 

Fdison                       

.67 

11 

07 

250  MILITARY  SIGNAL  CORPS  MANUAL 

GRAVITY    CELL 

This  is  the  form  of  primary  cell  most  extensively  used  in 
telegraphy  and  telephony  when  a  small  but  constant  current  is  re- 
quired. The  usual  form  is  shown  in  figure  4. 

These  cells  have  been  furnished  previously  in  two  sizes,  each 
being  designated  by  dimensions  of  containing  jar.  One  size  is 
6  by  8  inches  and  the  other  is  5  by  7  inches.  The  latter  size  has 
been  recently  adopted  by  the  Signal  Corps  as  standard,  and  this 
size  only  will  hereafter  be  issued.  In  the  bottom  of  the  jar  are 
placed  three  strips  of  sheet  copper,  riveted  together,  as  shown  in 


FIG.   4.— GRAVITY    BATTERY   CELL 


the  figure,  with  a  rubber-insulated  wire  attached  to  one  of  the 
strips.  There  are  many  forms  of  zinc,  but  the  "crowfoot"  is  the 
form  now  almost  universally  used. 

To  set  up  the  cell,  place  about  3  pounds  of  bluestone  (sulphate  of 
copper)  in  the  cell  after  putting  in  the  copper,  then  hang  the  zinc 
and  fill  with  water.  The  bluestone  should  be  allowed  to  settle 
without  any  attempt  to  dissolve  it  by  stirring  or  other  means.  The 
cell  or  cells  are  then  "short-circuited"  (zinc  and  copper  connected 
together)  and  allowed  to  stand  several  days.  By  that  time  part  of 
the  bluestone  will  have  dissolved,  the  blue  line  being  well  de- 
fined. Above  this  will  be  a  clear  solution  of  sulphate  of  zinc, 
formed  by  the  action  of  the  battery :  the  sulphate  of  zinc,  being  of 
less  specific  gravity  than  the  copper  sulphate  solution,  will  remain 


TELEGRAPHY  AND  TELEPHONY  251 

on  top  if  the  cell  is  not  shaken  or  stirred  up.  The  battery  may 
now  be  put  into  service. 

If  in  a  hurry  for  the  cell,  it  may  be  started  off  at  once  by  stirring 
up  about  a  tablespoonful  of  salt  with  the  water  before  pouring  into 
the  cell ;  but  this  method  is  likely  to  make  a  battery  dirty  and  con- 
siderably shorten  its  period  of  usefulness.  Any  long,  dark  masses 
forming  on  the  lower  part  of  the  zinc  should  be  removed  with  a 
stick.  The  zinc  sulphate  solution  will  grow  stronger  and  stronger, 
until  finally  the  white  salts  will  begin  to  creep  or  climb  up  the 
sides  of  the  jar  and  the  zinc.  As  they  will  corrode  the  connections 
and  cause  dirt  and  loss  of  insulation  around  the  cells,  they  should 
be  removed.  Much  of  the  trouble  will  be  obviated  if,  as  soon  as 
they  appear,  part  of  the  zinc  sulphate  solution  is  drawn  off  with  a 
battery  syringe  or  a  siphon  made  of  bent-glass  tube,  and  water  put 
in  its  place.  If  the  upper  parts  of  the  cells  are  warmed  and  smeared 
with  paraffin  it  will  help  matters.  But  the  best  plan  of  preventing 
evaporation  and  creeping  of  salts  is  to  use  a  good  quality  of  paraffin 
or  lubricating  oil,  pouring  on  a  layer  about  one-fourth  inch  thick 
as  soon  as  the  cells  are  set  up.  In  cleaning  cells  after  that,  wet 
cotton  waste  dipped  in  sand  will  clean  the  zincs,  etc.,  of  the  adher- 
ing oil.  As  soon  as  the  blue  solution  goes  down  below  the  level  of 
the  copper  more  bluestone  should  be  added.  Corrosion  of  the  con- 
nections of  the  zincs  with  their  wires  should  be  carefully  looked 
after.  It  is  better  to  have  routine  inspections  of  batteries  made, 
and,  if  practicable,  instrumental  tests  made  with  the  voltmeters  or 
voltammeter  B_,  thi.  meat  deterioration  may  be  accurately  noted 
and  many  annoyances  breakdowns  and  delays  which  are  frequently 
due  to  neglect  and  lack  of  regular  inspection  of  the  batteries  may  be 
avoided. 

The  internal  resistance  of  a  gravity  cell  in  good  condition  will 
be  found  to  be  about  .3  ohms,  its  E.M.F.  1  volt. 

FULLER  BATTERY 

This  belongs  to  the  class  popularly  called  "acid  batteries."  The 
cell  has  a  high  electromotive  force,  a  comparatively  low  internal 
resistance  (0.5  ohm),  and  is  much  used  as  transmitter  battery  on 
long-distance  heavily  worked  telephones  or  local  battery  telephone 
switchboards.  Its  only  disadvantage  is  that  it  uses  a  corrosive 
solution  containing  sulphuric  acid,  necessitating  much  care  in 
handling.  It  consists  of  a  glass  jar  about  8  inches  high  and  6 
inches  in  diameter,  with  a  wooden  cover  treated  with  asphaltum  or 
P.  &  B.  paint.  Figure  5  illustrates  this  cell.  The  cover  supports  a 
carbon  plate  about  4  inches  wide,  9  inches  long,  and  one-fourth  inch 
thick,  with  the  top  coated  with  paraffin  to  prevent  the  corrosion  of 
the  connection  by  the  acid.  In  the  jar  stands  an  earthenware  porous 
cup  7'4  by  3  inches,  in  the  bottom  of  which  is  placed  about  2  ounces 


252 


MILITARY  SIGNAL  CO.\TS  MANUAL 


of  mercury.  In  this  stands  a  conical  zinc  cast  to  a  copper  wire  which 
extends  out  at  the  top.  In  the  glass  jar  is  placed  the  "electropion" 
solution,  made  by  slowly  adding  1  pound  of  strong  sulphuric  acid 
to  9  pounds  of  distilled  water,  and  then  stirring  in  3  pounds  of 
pulverized  bichromate  of  potash  or  2]/2  pounds  of  bichromate  of 
sodium.  This  last  is  preferable,  as  the  crystals  formed  in  the 
action  of  the  cell  are  not  so  hard  and  insoluble  as  those  produced 
by  the  potash.  In  the  porous  cell  with  the  zinc  and  mercury  is 
placed  water  in  which  about  a  tablespoon ful  of  salt  has  been  dis- 
solved. This  cell  will  usually  require  little  attention  for  three  or 
four  months.  When  the  solution  assumes  a  muddy  bluish  tint  it  is 
about  exhausted. 

If  the  copper  wire  at  its  junction  with  the  zinc  is  covered  with 


FIG.    5.-FULLER    BATTERY   CELL 


paraffin  or  ozite,  or  if  the  copper  wire  is  well  amalgamated  by  rub- 
bing with  mercury  after  dipping  it  into  acid,  the  wire  does  not  tend 
to  be  eaten  off  at  the  junction,  as  it  otherwise  does  under  heavy 
service.  The  Signal  Corps  issues  the  materials  for  the  solution  in 
dry  form,  which  when  dissolved  form  the  electrolyte  This  is  pur- 
chased under  various  commercial  names  as  chromac,  voltac,  chro- 
mite,  salts,  etc.,  the  first  being  the  usual  designation.  It  is  packed 
in  tin  cans  with  thin  cut-out  top,  containing  1  pound,  which  is  the 
amount  for  one  charge.  Full  directions  for  using  are  marked  on 
each  can. 

The  carbon  of  this  cell  lasts  indefinitely,  but  should  be  soaked 
in  warm  water  when  renewals  are  made.  The  zinc  may  last 
through  several  renewals  of  the  electropion  fluid.  The  mercury 
should  be  saved  and  used  repeatedly. 


TELEGRAPHY  AND  TELEPHONY 


253 


The  following  table,  quoted  from  "Abbott's  Telephony,"  in- 
dicates the  effect  of  age  on  efficiency  of  transmission  with  the 
Fuller  cell. 

TWO-CELL    FULLER    BATTERY 


Age 

Volume   of 
Transmission 

Age 

Volume   of 
Transmission 

Days 

20 
30 
40 
50 

Per  Cent. 
92 
88 

84 
80 

Days 
60 

70 
80 
90 

Per  Cent. 
76 

70 
62 
54 

From   this   it  would  appear   that   the  cells   must  be   renewed  at 


•H 


FIG.    6-TYPE  V  EDISON  PRIMARY  BATTERY  CELL 
least  once  in  three  months  when  used  on  a  telephone  transmitter. 


EDISON    PRIMARY   BATTERY 

The  type  V  cell  shown  in  figure  6  is  the  standard  Edison  cell. 
As  previously  manufactured  for  the  Signal  Corps,  it  has  the  same 
capacity  as  the  old  Edison  La  Lande  cells,  but  its  enamelled  steel 
jar  was  slightly  conical,  enabling  the  cells  to  be  nested  together  for 
transportation.  The  caustic  soda  and  oil  for  each  cell  are  issued 
in  tin  cans,  so  that  there  is  nothing  that  will  not  stand  transporta- 
tion. This  cell  has  a  very  low  internal  resistance  (not  exceeding 
one-eighth  ohm)  and  will  remain  set  up  on  open  circuit  for  a  long 
time  with  very  little  depreciation.  It  has  a  capacity  of  about  150 
ampere  hours,  which  means  that  it  will  furnish  about  210  days' 


254  MILITARY  SIGNAL  CORPS  MANUAL 

continuous  service  on  a  line  where  the  current  is  30  milliamperes  and 
40  days'  service  when  the  current  is  about  0.16  ampere.  It  gives 
but  0.67  volt  E.M.F.  in  steady  work. 

The  following  complete  directions  for  setting  up,  management, 
and  renewal  of  these  cells  are  furnished  by  the  company  manu- 
facturing them : 

DIRECTIONS     FOR     SETTING     UP     AND     USING     EDISON     PRIMARY     BATTERY, 

KNOWN    AS    EDISON    CELL,    TYPE    V 
TO    CHARGE    AND    CONNECT    BATTERIES 

To  make  solution — Fill  the  cells  with  water  to  ll/2  inches  of  the 
top.  Add  the  caustic  soda  gradually  to  the  water,  stirring  until  the 
soda  is  entirely  dissolved.  When  the  solution  cools,  more  should 
be  added  to  bring  it  up  to  \l/2  inches  of  the  top.  Then  pour  con- 
tents of  bottle  of  heavy  paraffin  oil  from  bottle  furnished 
for  each  jar  on-  the  solution.  Note — The  caustic  soda  will  burn 
the  skin  and  clothes.  In  stirring  the  liquid  avoid  splashing  it. 

To  set  up  cells — Unscrew  the  nut  N  and  the  jamb  nut  M  from 
the  screw  on  the  brass  neck  of  the  double  zinc  plate  and  remove  the 
leather  washer.  Pass  the  screw  from  below  through  the  central 
hole  in  the  cover  C.  Replace  the  leather  washer  and  the  jamb  nut 
M  on  the  screw  and  tighten  down  the  jamb  nut  until  the  zinc 
plate  is  rigid  to  the  cover.  The  thumb  nut  X  can  then  be 
screwed  on. 

Unscrew  the  nuts  A  A  and  jamb  nut  D  from  the  screws  on 
the  two  side  pieces  B  B  of  the  copper  frame,  leaving  the  flat 
leather  washers  in  position  on  the  screws,  and  pass  the  screws  from 
below  through  the  two  round  holes  in  the  cover  C.  Replace  the 
jamb  nut  on  one  of  the  screws  and  one  of  the  thumb  nuts  on  the 
other  screw,  and  tighten  both  down  until  the  frame  sides  are 
rigidly  clamped  to  the  cover.  Replace  the  other  thumb  nut  on 
the  screw  holding  jamb  nut.  Then  slip  the  hard  rubber  insulating 
tubes  E  E  over  the  sides  of  the  frame,  one  on  each  side. 

To  fill  copper  frames — (In  this  cell  only  one  oxide  plate  is 
used.)  (See  figure  6.)  Slide  the  oxide  plate  F  sufficiently  far  into 
the  frame  to  enable  the  copper  bolt  G  to  be  passed  underneath  it 
through  the  slots  in  the  bottom  of  the  frame  sides  and  the  copper 
nut  H  tightened  up  on  same.  Be  careful  that  the  zinc  plates  do 
not  touch  the  copper  oxide  plates  or  the  cell  will  be  short-circuited. 
The  copper  connection  is  made  between  the  thumb  nut  A  and 
the  jamb  nut  D  on  one  end  of  the  copper  frame  and  the  zinc  con- 
nection between  the  thumb  nut  N  and  the  jamb  nut  M  on  the  brass 
bolts  suspending  the  zincs.  After  the  oxide  and  zinc  plates  are 
properly  connected  to  the  cover,  soak  them  in  water  and  while  still 
wet  insert  in  jar  filled  with  caustic  solution.  (Wetting  the  plates 
prevents  the  oil  in  jar  from  adhering  to  them.) 


TELEGRAPH  V  AND  TELEPH ONY  255 

Important— In  order  to  allow  the  cover  on  the  jar  to  fit  easily, 
it  is  advisable  to  wet  the  rubber  gasket  ring  fitting  into  the  grooved 
edge  of  the  cover  by  placing  it  in  water.  This  will  cause  the  cover 
to  slip  on  easily  and  will  make  the  cell  liquid  tight.  It  is  absolutely 
necessary  that  the  upper  edge  of  the  oxide  plates  should  be  sub- 
merged at  least  1  inch  below  the  surface  of  the  caustic  soda 
solution  in  the  jar;  also  on  no  account  can  the  layer  of  oil  on  top 
of  the  solution  be  omitted. 

RENEWING 

When  the  cell  becomes  exhausted  the  solution  and  the  remains 
of  the  zinc  and  oxide  plates  must  be  thrown  away.  The  remaining 
parts  can  be  used  again. 

TO    TAKE   THE   CELLS    APART 

Lift  the  lids,  unscrew  the  bolts,  and  remove  the  zincs  and  oxide 
plates.  Wash  off  (with  water)  the  copper  frames,  bolts,  and  rubber 
insulators,  brightening  up  the  metal  where  corroded  with  emery 
paper,  especially  the  inside  grooves  of  the  copper  frame  sides. 
Pour  away  th-i  solution  carefully  and  set  up  cells  with  new  caustic 
soda,  oxide  plates,  and  zincs  according  to  directions. 

Note — In  taking  the  cells  apart  the  parts  that  have  been  immersed 
in  the  caustic  soda  must  be  washed  before  they  are  handled. 

TO    ASCERTAIN    IF    THE    OXIDE    PLATES    ARE    EXHAUSTED 

Pick  into  the  body  of  the  oxide  plates  with  a  sharp-pointed 
knife.  If  they  are  red  throughout  the  entire  mass,  they  are  com- 
pletely exhausted  and  need  renewing.  If  on  the  contrary,  there 
is  a  layer  of  black  in  the  interior  of  the  plate,  there  is  still  some 
life  left,  the  amount  being  dependent  entirely  upon  the  thickness 
of  the  layer  of  black  oxide  still  remaining. 

COPPER   FRAMES 

When  renewing  the  battery  it  is  desirable  to  clean  the  inside 
grooves  of  the  copper  frames,  where  the  copper-oxide  plates 
make  contact,  so  as  to  insure  a  good  electrical  connection.  This  is 
especially  important  where  the  batteries  are  required  to  give  a  heavy 
current  for  cautery  or  motor  purposes.  These  frames  can  be 
easily  cleaned  by  wrapping  a  small  piece  of  emery  paper  around  a 
stick  which  will  just  fit  into  the  groove,  or  by  immersing  them 
in  a  diluted  solution  of  1  part  of  sulphuric  acid  and  4  parts  water, 
and  then  carefully  rinsing  them  in  clean  water  to  remove  all  traces 
of  the  acid. 

Caution — The   oxide  plates   should  never  be   removed    from   the 


256  MILITARY  SIGNAL  CORPS  MANUAL 

caustic  soda  solution  and  allowed  to  dry  in  the  air,  as,  if  this 
is  done,  the  surface  of  the  plates  becomes  oxidized  by  absorbing 
the  oxygen  from  the  air,  and  the  oxide  thus  found  is  much 
more  difficult  of  reduction  than  the  original  oxide  of  which  the 
plates  are  formed.  The  internal  resistance  is  consequently  very 
greatly  increased  and  the  current  materially  diminished. 

Note — Where  batteries  are  placed  in  warm  places  they  should  be 
examined  every  two  or  three  months  to  see  that  the  solution  has 
not  evaporated,  as  this  will  gradually  take  place,  in  spite  of  the 
oil,  if  they  are  in  a  hot  room.  If  the  solution  is  found  to  have 
evaporated,  add  more  water  to  bring  it  again  to  the  proper  height. 
It  is  of  the  first  importance  that  all  binding  posts  and  connecting 
wires  should  be  kept  clean  and  bright  at  the  points  of  connection. 

The  type  V  cell  is  excellent  for  use  as  an  ignition  battery  or  in 
lieu  of  small  capacity  storage  batteries  where  no  charging  current 
exists.  The  Signal  Corps  uses  this  type  of  battery  quite  exten- 
sively in  connection  with  the  Alaska  Military  Cable  and  Telegraph 
System. 


GROUPING  OF  CELLS 

When  it  is  necessary  to  cause  a  certain  current  to  flow  through 
a  considerable  resistance,  as  a  long  telegraph  line,  for  instance,  the 
necessary  E.M.F.  is  obtained  by  connecting  cells  in  series — that  is, 
the  copper  of  one  cell  to  the  zinc  of  the  next,  and  so  on  until  the 
requisite  E.M.F.  is  obtained,  the  relatively  small  increase  of  the 
total  resistance  due  to  the  internal  resistance  of  the  cells  being  of 
little  effect.  The  total  voltage  is  the  sum  of  the  voltages  of  all  the 
units  so  connected.  But  when  it  is  desired  to  get  a  certain  current 
through  a  low  resistance,  another  grouping  must  be  made.  The 
internal  resistance  of  the  ordinary  gravity  cell  is  about  3  ohms. 
And  with  its  one  volt  E.M.F.  the  current  through  a  short  thick 
wire  of  no  appreciable  resistance  connecting  its  poles  will  be  one- 
third  ampere.  And  if  we  have  100  cells  in  series  and  connect  the 
terminals  of  the  entire  battery,  we  would  get  100  ampere,  or  one- 

300 

third,  as  before.  For  any  number  of  these  cells  in  series,  to  obtain 
an  increased  current  through  low  external  resistance,  we  must  cut 
down  the  internal  resistance  of  our  battery.  This,  with  a  given 
type  of  cell,  may  be  done  by  linking  them  in  parallel — that  is,  by 
connecting  all  the  zincs  together  and  all  the  coppers  together  and 
then  connecting  the  multiple  zinc  and  multiple  copper  thus  ob- 
tained to  the  low  external  resistance.  The  E.M.F.  of  the  battery 
remains  the  same  as  that  on  one  cell,  but  the  current  output  is 


TELEGRAPHY  AND  TELEI'/IOXY 


257 


now  equal  to   the  sum  of  the  current  capacities  of  all  the  units 
so  connected. 


FIG.  7.— BATTERY  CELLS  CONNECTED  IN  SERIES 


Figure  7  shows  four  cells  of  battery  connected  in  series,  and 
figure  8  shows  four  cells  of  battery  connected  in  multiple,  or  parallel, 
as  it  is  sometimes  called.  In  the  first  case  we  should  get  a  current 
of  (4-H2)  =  (l-f-3)  ampere  through  our  short  circuit;  and  in 
the  second  case  I=l-:-34=(4-^3)  ampere. 

While  in  both  figures  the  gravity  cell  is  shown,  the  rule  is  ap- 
plicable to  any  type,  class,  or  make  of  primary  or  secondary 
battery  cells. 

Number  and  kind  of  battery  cells  required   by  various  apparatus. 

(Where  more  than  one  battery  cell  is  indicated  the  cells  are  invariably 
connected   in    series.) 


Instrument 

Cell 

Number  of  Cells 

3 

L.    B.   post-telephone   switchboard1  

Fuller  

2 

Camp  switchboard  

No.   6  reserve  
do  

2 
2 

Camp    telephone  

Type   A   tungsten., 
do  

1     unit     (2    cells) 
2    units    (4    cells) 

do  

do 

do 

Flash-light    

do  

1     unit     (2     ceils) 

1Either  gravity  or  Fuller  may  be  used  for  operator's  transmitter 
circuit.  In  addition,  2  cells  of  No.  6  reserve  may  be  used  for  night 
alarm. 

SECONDARY  BATTERIES 

The  storage  battery  differs  from  the  primary  battery  in  its  action 
in  that  when  it  has  given  out  all  the  energy  the  chemicals  present 
enable  it  to  supply,  instead  of  requiring  new  elements,  the  cell  can 
be  completely  regenerated  or  brought  back  to  its  original  charged 


258 


MILITARY  SIGXAL  CORPS  MAXTAL 


condition  by  passing  a  current  into  it  in  a  direction  opposite  to  that 
in  which  the  flow  took  place  on  discharge. 

Although  there  are  many  combinations  which  can  be  used  for 
storage  batteries,  a  large  majority  of  those  in  commercial  use  and  all 
those  installed  by  the  Signal  Corps  are  of  the  lead-sulphuric  acid  type, 
which  in  its  basic  principle  consists  of  two  especially  prepared  dis- 
similar lead  plates  immersed  in  diluted  sulphuric  acid.  Each  cell 
of  the  lead-sulphuric  acid  storage  battery  has  an  E.M.F.  of 
about  2.05. 

The  Edison  storage  battery,  which  has  recently  been  developed 
and  placed  on  the  market,  makes  use  of  oxides  of  nickel  and  iron 
in  the  positive  and  negative  electrodes  respectively.  The  grids 
supporting  the  active  material  are  made  of  nickel-plated  steel,  and 
the  electrolyte  is  a  solution  of  caustic  potash  and  water.  These 
cells  when  fully  charged  have  a  normal  E.M.F.  of  1.2  volts  and 
are  charged  at  about  1.7  volts.  They  stand  abuse  much  better  than 
the  lead-sulphuric  type  of  battery  and  are  highly  advantageous  for 
vehicle  purposes,  as  it  is  claimed  the  output  per  unit  of  weight 
is  nearly  twice  that  of  lead  cells.  An  idea  of  the  ruggedness  of 
this  battery  may  be  had  when  consideration  is  given  to  the  fact 
that  when  the  battery  becomes  unhealthy  or  impaired  by  lack  of 
work,  or  too  much  work,  short  circuiting  the  battery  for  a  moderate 
period  will  assist  in  returning  the  battery  to  a  healthy  condition. 

Secondary  batteries  in  the  form  of  storage  batteries  or  accumu- 
lators are  used  by  the  Signal  Corps  for  supplying  necessary  current 
in  connection  with  comparatively  large  telephone  systems,  sig- 
naling systems,  and  telegraph  systems  where  a  suitable  charging 
circuit  is  available.  When  used  for  supplying  current  for  the 
operation  of  post  telephone  systems,  the  svstems  are  invariably 


FIG.  8.— BATTERY  CELLS  CONNECTED  IN  MULTIPLE 


what    are    termed    "common-battery"    or    "central-energy"    systems. 
With  this  type  of  system  the  current  for  operation  of  all  apparatus 


TELEGRAPH?  AND  TELEPHONY  259 

is  obtained  from  one  battery.     In  a  local-battery  telephone  system 
the  switchboard  and  each  telephone  is  equipped  with  a  battery. 

In  fire-control  systems  at  sea-coast  defenses  15  cells  of  storage 
battery,  connected  in  series,  are  installed  for  supplying  current  for 
operation  of  the  telephone  system  of  the  fire-control  system  proper, 
and  in  a  great  many  instances  the  same. battery  furnishes  current 
necessary  in  the  operation  of  the  entire  post  telephone  system.  In 
emergency  the  same  battery  may  also  be  used  to  supply  all  signal 
apparatus  of  the  fire-control  system,  which  normally  is  supplied 
by  current  obtained  from  a  motor  generator  set,  the  motor  gener- 
ator set  being  used  to  charge  the  storage  battery  when  operation 
of  the  system  is  not  in  progress. 

Either  a  battery  of  12  cells  or  a  battery  of  15  cells  of  storage 
battery,  connected  in  series,  are  installed  for  supplying  necessary 
current  for  operation  of  common-battery  post  telephone  systems  at 
interior  posts. 

GENERAL   DATA   CONCERNING  THE   STORAGE  BATTERY 

The  elementary  form  of  storage  cell  is  made  by  immersing  two 
lead  plates  in  dilute  sulphuric  acid.  The  principle  involved  in  the 
storage  cell  is  the  chemical  action  produced  by  a  current  which 
causes  such  changes  of  the  lead  plates  in  the  acid  that  upon  cessation 
of  the  current,  if  the  two  plates  are  connected  together  by  a  wire,  a 
current  will  flow  in  the  opposite  direction  from  the  original  one 
and  the  plates  will  tend  to  return  to  their  original  condition. 

The  action  of  the  current  is  to  coat  the  plate  that  is  connected 
with  the  positive  pole  of  the  charging  dynamo  with  peroxide  of 
lead,  and  to  reduce  to  a  spongy  metallic  condition  the  surface  of 
the  plate  connected  with  the  negative  pole.  When  the  plates  are 
connected  by  a  wire  the  peroxide  coating  tends  to  be  reduced  back 
to  lead  and  the  spongy  lead  on  the  other  plate  to  become  oxidized. 
The  plates  thus  becoming  alike  the  current  will  cease  and  the  cell 
is  said  to  be  discharged.  Various  methods  of  manufacture  are  in- 
tended to  give  the  plates  more  capacity ;  that  is,  to  prepare  more 
reducible  peroxide  on  one  and  more  spongy  lead  on  the  other.  The 
means  adopted  are  to  make  the  plates  up  in  the  form  of  fine  strips 
or  grids  of  lead  and  fill  in  these  interstices  with  the  oxides  of  lead 
by  various  processes.  These  plates,  being  made  up  in  sets,  are 
then  immersed  in  acid  and  given  what  is  called  a  "forming  charge," 
after  which  they  may  be  used. 

The  plates  as  received  from  the  manufacturer  are  of  two  kinds. 
The  sets  of  plates  of  one  kind  are  of  a  chocolate  brown,  while 
the  other  sets  are  of  a  grayish  leaden  color.  When  these  are 
jtlaced  in  the  jars  the  sets  of  plates  represent  the  zinc  and  copper, 
respectively,  of  a  primary  battery,  the  gray  plates  acting  as  zincs 
and  the  brown  as  copper.  In  connecting  cells  in  series  the  brown 


260  MILITARY  SIGNAL  CORPS  MAXl'AL 

set  of  one  cell  should  be  connected  with  the  gray  set  of  another, 
and  so  on.  Care  should  be  taken  that  no  plates  of  different  kinds 
touch  on  the  inside  of  cells,  and  that  the  separators  are  prop- 
erly placed,  if  these  are  furnished  with  the  kind  of  cell  used. 
The  connecting  lugs  should  all  be  brightened  before  they  are 
bolted  together,  and  af.ter  all  connections  are  made  it  is  well 
to  go  over  them  with  a  coating  of  cosmoline  or  asphaltum  varnish. 
The  cells  should  always  be  set  up  in  a  dry  place,  preferably  where 
there  is  a  good  means  of  lighting  and  where  there  may  be  ample 
ventilation. 

The  first  or  initial  charge  of  any  storage  battery  takes  a  much 
greater  length  of  time  than  the  subsequent  regular  charges.  The 
initial  charge  of  any  make  of  storage  battery  should  be  continuous 
if  possible.  With  most  batteries  it  takes  from  50  to  60  hours  to 
complete  the  initial  charge,  while  the  regular  charge  thereafter 
should  be  completed  in  approximately  eight  hours  at  the  normal 
rate.  The  battery  should  be  discharged  below  1.70  volts  per  cell. 

Purity  of  electrolyte  is  of  first  importance  in  storage  battery 
operation,  and  all  acid  should  be  tested  where  a  doubt  as  to  its 
purity  exists. 


TELEPHONY— THE   CAMP    TELEPHONE   AND   THE 
BUZZER 

MAGNETISM 

A  bar  of  steel  or  iron  which  has  the  properties  of  attracting  other 
pieces  of  steel  or  iron  is  called  a  magnet.  When  freely  suspended 
at  its  center  it  will  point  north  and  south.  It  can  also  impart 
these  powers  to  another  piece  of  iron  or  steel  without  losing  any 
of  its  own. 

The  ends  of  a  magnet  are  called  its  poles.  The  end  which  points 
toward  the  north  is  its  north  pole  and  the  other  end  its  south  pole. 
The  north  end  of  any  magnet  will  repel  the  north  ends  of  all  other 
magnets,  but  will  attract  all  south  poles.  From  this  follows  the 
law  of  magnetic  attraction  "like  poles  repel  and  unlike  poles 
attract." 

The  force  exerted  by  one  magnet  on  another  to  attract  or  repel 
it  is  called  magnetic  force.  If  iron  filings  be  spread  on  a  paper  laid 
over  a  bar  magnet,  the  filings  will  arrange  themselves  about  the 
magnet  in  curves  which  end  at  the  poles.  These  curves  are  called 
lines  of  force,  and  the  whole  space  occupied  by  the  curves  is  the 
magnetic  field  of  force,  or  magnetic  field.  It  is  assumed  that  the 
lines  of  force  come  out  from  the  north  pole  of  the  magnet,  pass 
through  the  air,  re-enter  the  magnet  at  the  south  pole  and  pass 
through  it  to  the  north  pole,  thus  completing  the  path.  This  path 
forms  the  magnetic  circuit,  and  each  of  the  lines  of  force  com- 
pletes it  without  crossing  or  combining  with  any  one  of  the  others 
in  the  field.  A  line  of  force  always  forms  a  closed  loop  so  that 
as  many  lines  enter  the  south  pole  as  leave  the  north. 

To  make  a  magnet  of  a  steel  bar,  place  the  bar  flat  on  a  table. 
Take  the  south  pole  of  a  magnet  and  stroke  the  bar  with  it  several 
times,  always  from  end  to  end  in  the  same  direction.  The  end  of 
the  bar  first  touched  will  then  become  a  south  pole  and  the  end 
where  magnet  last  touched  a  north  pole.  The  bar  will  then  be  a 
magnet.  Or  wind  a  few  turns  of  insulated  wire  around  the  bar  and 

261 


262  MILITARY  S1GX.-IL  COh'l'S  M.-L\L'AL 

pass  a  current  of  electricity  through  the  wire  for  a  short  time, 
gently  tapping  the  bar  with  a  hammer  while  the  current  is  flowing. 
Upon  removing  the  bar  from  the  coil  it  will  be  found  to  be  a 
magnet. 

If  a  piece  of  iron,  mounted  on  a  pivot  so  it  is  free  to  swing 
about,  be  placed  in  a  magnetic  field  of  force,  the  iron  will  move 
so  that  the  greatest  number  of  lines  of  force  of  the  field  will  pass 
through  it.  If  the  movable  body  be  a  magnet,  for  example,  a  com- 
pass, it  will  turn,  under  the  influence  of  the  field,  so  that  not  only 
the  greatest  number  of  lines  of  force  will  pass  through  it,  but  also 
that  its  own  lines  of  force  will  be  in  the  same  direction  as  those  of 
the  field.  Upon  this  fact  is  based  the  construction  of  many  forms 
of  electrical  instruments. 

If  a  bar  of  soft  iron  be  placed  in  the  field  of  a  bar  magnet,  we 
will  find  on  testing  the  soft  iron  bar  that  it,  too.  has  become  a 
magnet  having  two  distinct  poles.  The  iron  bar  is  called  the  body 
under  induction,  the  magnet  the  inducing  body,  and  this  phenomenon 
magnetic  induction.  Magnetic  induction  is  defined  as  the  action 
and  reaction  which  occur  when  a  magnetic  field  makes  a  magnet  of 
a  body  placed  therein. 

ELECTROMAGNETISM 

Every  wire  through  which  a  current  flows  possesses  a  magnetic 
field  around  it.  This  fact  can  be  proved  by  bringing  a  compass  near 
it.  The  magnetic  field  will  act  on  the  compass,  and  the  needle  will 
be  deflected,  showing  not  only  the  presence  of  a  magnetic  field  but 
also  the  direction  of  the  lines  of  force.  These  will  be  found  to 
encircle  the  wire,  always  running  from  left  to  right,  similar  to 
the  direction  in  which  the  hands  of  a  clock  move,  assuming  that 
the  current  is  flowing  directly  away  from  the  observer. 

A  solenoid  consists  of  one  or  more  layers  of  wire  wound  on  a 
Spool,  usually  of  nonmagnetic  material,  the  length  being  great  as 
compared  with  the  diameter.  A  magnet  can  be  made  of  a  solenoid 
by  passing  a  current  of  electricity  through  the  wire.  One  end  of  the 
"coil  will  be  the  north  pole  and  the  other  the  south  pole.  If  an  iron 
bar  be  placed  lengthwise  through  the  coil  while  the  current  is  flow- 
ing, it  will  be  found  that  the  magnetism  has  been  increased.  This 
is  due  to  the  fact  that  lines  of  force  are  much  more  easily  set  up 
in  iron  or  steel  than  in  a  nonmagnetic  medium.  A  solenoid  with 
such  an  iron  core  constitutes  an  electromagnet.  The  current's 
magnetic  field  induces  magnetism  in  a  piece  of  iron  placed  within 
its  limits. 

If  the  iron  core  of  a  solenoid  is  pulled  out  while  the  current 
is  flowing  the  attractive  force  of  the  solenoid  will  tend  to  pull  the 
core  back  until  its  middle  point  coincides  with  that  of  the  solenoid. 
This  principle  is  made  use  of  in  many  electrical  devices,  such  as 


THE  CAMP  TELEPHONE  263 

circuit  breakers,  ammeters,  and  telautographs.  Electromagnets  are 
used  in  many  kinds  of  instruments — electric  bells,  telegraph 
sounders,  telephone  receivers  and  relays  are  examples.  The  strength 
of  any  electromagnet  depends  on  the  turns  of  wire  and  the  strength 
of  current  passing  through  it. 

ELECTROMAGNETIC  INDUCTION 

If  a  straight  wire  be  moved  across  a  magnetic  field  so  as  to  cut 
lines  of  force,  a  difference  of  potential  will  be  set  up  between  its 
ends.  If  the  ends  of  the  wire  be  connected  outside  the  field,  a 
current  will  flow.  This  is  called  electromagnetic  induction,  and  the 
currents  so  produced  are  induced  currents.  Upon  the  principle  of 
induction  is  based  the  operation  of  all  dynamos,  transformers,  in- 
duction coils,  telephones,  etc. 

No  distinction  is  made  between  the  magnetic  field  of  a  perma- 
nent steel  magnet  and  that  of  an  electromagnet.  Either  the  mag- 
netic field  or  the  closed  circuit  may  be  moved  so  long  as  the  lines 
of  magnetic  force  are  made  to  cut  the  wire  of  the  closed  circuit. 
Usually  a  coil  of  wire  with  an  iron  core  (electromagnet)  is  used 
to  produce  the  induction.  It  is  then  called  the  primary  coil,  or 
simply  "primary."  The  closed  circuit,  or  the  circuit  under  induc- 
tion, is  then  called  the  secondary  coil,  or  "secondary." 

Current  may  be  induced  in  the  secondary  by  any  of  the  following 
methods : 

1.  By  moving  either  the  primary  or  secondary  while  current  is 
flowing  in   the  primary. 

2.  By  making  or  breaking  the  primary  circuit. 

3.  By  altering  the  current  in   the  primary. 

4.  By  reversing  the  direction  of  current  in  the  primary. 

5.  By  moving  the  iron  core  while  current  flows  in  the  primary. 

ELECTROSTATIC    INDUCTION 

It  has  been  found  that  an  insulated  conductor,  such  as  a  sheet 
of  tin,  an  aerial-line  wire,  or  a  cable  conductor,  has  the  property 
of  receiving  an  electrostatic  charge  when  subjected  to  an  elec- 
tromotive force.  If,  for  instance,  a  conductor  of  the  type 
mentioned  in  the  preceding  paragraphs  be  thoroughly  in- 
sulated and  one  terminal  connected  to  one  side  of  a  battery, 
the  other  side  of  which  is  grounded,  a  certain  amount  of  electricity 
will  flow  into  the  conductor  and  appear  upon  its  surface  as  an 
electrostatic  charge,  and  the  potential  of  the  conductor  will  be  raised 
to  that  of  the  battery.  The  conductor  in  this  condition  is  said  to  be 
charged  and  holds  an  amount  of  electricity  depending  upon  its 
capacity.  The  charge  is  of  the  same  polarity  as  the  terminal  of 
the  battery  to  which  the  conductor  is  connected. 


264  MILITARY  SIGNAL  CORPS  MANUAL 

Experiment  has  determined  that  a  charge  can  not  exist  on  a  con- 
ductor except  there  be  an  equal  and  opposite  charge  induced  upon 
the  bodies  surrounding  it,  and  this  second  induced  charge  is  always 
of  opposite  polarity  to  that  of  the  first  charge.  If  now  the  con- 
ductor be  connected  to  the  ground  it  will  lose  its  charge,  but  the 
charge  of  opposite  sign  on  the  surrounding  bodies  will  still  be  held, 
although  having  no  connection  with  the  first  body  or  with  the  source 
of  electromotive  force.  This  action  by  which  bodies  are  charged 
through  an  insulating  medium  constitutes  electrostatic  induction, 
and  the  arrangement  of  two  insulated  conductors  separated  by  an 
insulated  medium  constitutes  a  condenser.  The  most  common  type 
of  condenser  is  the  Leyden  jar,  in  which  the  insulated  conductors 
are  sheets  \  of  tin  foil,  one  placed  on  the  outside,  the  second  on  the 
inside  of  the  glass  jar,  the  latter  forming  the  insulating  medium  or 
dielectric,  as  it  is  commonly  called.  The  capacity  of  the  condenser, 
or  its  ability  to  receive  an  electric  charge,  varies  in  direct  proportion 
to  the  area  of  its  plates  inversely  as  the  square  of  the  distance 
between  the  plates  and  directly  as  the  specific  inductive  capacity 
of  the  dielectric.  Where  air  is  used  as  the  dielectric,  this  latter 
quantity  is  unity.  The  substances,  other  than  air,  ordinarily  used 
as  dielectrics  have  a  specific  inductive  capacity  two  to  three 
times  as  great  as  that  of  air.  Condensers  used  for  telephone  pur- 
poses where  it  is  necessary  to  obtain  considerable  capacity  in  very 
limited  space,  are  commonly  built  up  of  alternate  layers  of  tin  foil 
and  paraffined  paper  tightly  pressed,  so  as  to  bring  the  layers  of  tin 
foil  which  comprise  the  plates  as  close  together  as  possible.  The 
condenser  is  very  extensively  used  in  telegraph  and  telephone  work 
as  a  means  of  allowing  alternating  or  pulsating  currents  to  pass 
while  preventing  the  flow  of  direct  currents.  This  is  the  direct 
opposite  of  the  functions  of  an  impedance  coil,  which  imposes  a 
very  high  resistance  to  variable  currents  while  offering  little  resist- 
ance to  the  flow  of  direct  current. 

PRINCIPLE  OF  THE   TRANSFORMER 

An  induction  coil,  or  transformer,  consists  of  two  independent 
coils  wound  on  the  same  iron  core  and  insulated  from  each  other 
and  from  the  core.  Alternating  or  interrupted  currents  in  one  of 
the  coils  (called  the  primary)  produce  a  variable  number  of  lines  of 
magnetic  force  in  the  iron  core,  and  thus  currents  are  induced 
in  the  other  coil  (secondary),  so  that  any  E.  M.  F.  that  may  be 
applied  to  the  primary  may  be  changed  to  a  higher  or  lower  one  in 
the  secondary.  The  ratio  of  primary  to  secondary  E.  M.  F.  is  equal 
to  the  ratio  of  the  turns  in  the  two  coils.  For  example,  if  there 
are  10  turns  in  the  primary  and  100  turns  in  the  secondary,  the  in- 
duced E.  M.  F.  will  be  10  times  greater  than  that  used  in  the 
primary.  When  a  low  E.  M.  F.  in  the  primary  is  changed  to  a 


THE  CAMP  TELEPHONE  265 

higher  one  in  the  secondary  coil,  the  latter  loses  in  current  strength 
what  it  gains  in  pressure.  For  example,  in  this  case,  if  there  is 
1  ampere  current  at  10  volts  pressure  in  the  primary  and  the  E.  M.  F. 
of  the  secondary  is  100  volts,  only  0.1  of  an  ampere  of  current 
would  be  flowing  through  the  latter.  This  assumes  that  there  are 
no  losses  in  the  transformer.  This  principle  is  made  use  of  to 
generate  very  high  electromotive  forces  such  as  are  used  in  wire- 
less telegraphy. 

THEORY  OF  THE  TELEPHONE 

In  the  act  of  speaking  the  vocal  cords  cause  air  vibrations, 
which,  falling  upon  the  drum  of  the  ear,  are  recognized  by  the 
auditory  nerves  as  speech.  If,  instead  of  falling  on  the  eardrum, 
these  vibrations  should  fall  upon  a  diaphragm  which  is  capable  of 
changing  them  into  electrical  vibrations,  and  there  is  some  means 
of  transmitting  them  along  a  line  and  again  reproducing  them  at  the 
other  end  into  similar  air  vibrations,  we  have  the  telephone.  In 
order  to  understand  the  action  of  the  telephone  it  is  necessary  to 
define  line>  of  force  and  explain  two  simple  laws  of  magnetic  in- 
duction. Lines  of  force  are  imaginary  lines  which  surround  a 
magnet  and  indicate  by  their  position  and  number  the  direction  and 
strength  of  its  action.  The  laws  of  magnetic  induction  referred  to 
are:  First,  if  a  number  of  lines  of  force  thread  or  pass  through  a 
coil  of  wire  and  this  number  is  increased  or  diminished,  a  momen- 
tary current  will  flow  in  the  coil ;  second,  .if  a  coil  of  wire  be  wound 
around  a  permanent  steel  magnet  and  a  current  of  electricity  be 
sent  through  the  windings,  it  will,  if  in  a  certain  direction,  increase 
the  strength  of  the  permanent  magnet,  and  if  in  the  opposite  direc- 
tion will  diminish  its  strength.  To  understand  how  articulate  speech 
is  transmitted  by  means  of  the  telephone,  let  us  take  the  simplest 
case  of  two  telephone  receivers,  A  and  B,  connected  to  the  line  as 
shown  in  figure  1. 


FIG.  1.— TELEPHONE  CIRCUIT  SIMPLIFIED,  USIXG  TWO 
TELEPHONE    RECEIVERS 


266 


MILITARY  SIGX.IL  CORPS  MANL'.U. 


The  telephone  receiver  (a  more  detailed  description  of  which 
will  appear  later)  consists  of  a  soft-iron  diaphragm  placed  close  to 
a  permanent  magnet.  Around  the  diaphragm  end  of  this  magnet 
is  wound  a  coil  of  fine  insulated  copper  wire.  The  air  vibrations^ 
caused  by  the  act  of  speaking,  upon  striking  the  iron  diaphragm  at 
A  cause  it  to  vibrate.  The  vibrations  of  this  diaphragm  produce 
changes  in  the  number  of  lines  in  force  which  thread  through  the 
windings  of  the  coil.  These  changes,  according  to  the-  first  law, 
produce  a  current  in  the  winding  which  will  be  of  greater  or  less 
strength  and  in  opposite  directions,  following  the  vibrations  of  the 
diaphragm.  This  varying  current  proceeds  along  the  line,  and 
when  it  arrives  at  B  will  increase  and  diminish  the  strength  of  B's 
magnet.  The  variation  of  the  strength  of  B's  magnet  will  produce 
a  varying  pull  on  B's  diaphragm  and  cause  it  to  vibrate  in  a  manner 
similar  to  the  diaphragm  of  A.  The  vibration  of  the  diaphragm  at 
B  is  recognized  as  sound  coming  from  A.  The  simple  circuit  shown 
in  figure  1  would  permit  a  person  to  talk  or  hear,  as  the  case  may 
be.  The  first  modification  of  the  circuit  (fig.  2)  is  to  introduce 
two  telephone  receivers  at  the  point  A  and  two  at  the  point  B,  all 
being  in  series,  one  serving  as  the  transmitting  and  the  other  as 
the  receiving  instrument  at  each  point. 

For  certain  reasons  this  type  of  receiver  just  described  does 
not  make  a  good  transmitter,  and  in  practice  is  replaced  by  a 
battery  transmitter. 

A  complete  local  battery  telephone  instrument  consists  of  a 
receiver,  local  battery  transmitter,  induction  coil,  magneto  generator, 
call  bell,  and  certain  switching  devices  which  are  contained  in  the 
magneto-generator  box. 


FIG.  2.— TELEPHONE  CIRCUIT  SIMPLIFIED,  USING  FOUR 
TELEPHONE  RECEIVERS 


A  complete   common   battery   instrument   consists   of   a   receiver, 
transmitter,  induction  coil,  condenser,  call  bell,  and  hook  switch. 


TIlll   CAMP   TELEPHONE 


LOCAL    BATTERY    TRANSMISSION 


267 


The  battery  transmitter  depends  for  its  action  on  the  fact  that 
a  varying  pressure  changes  the  resistance  of  carbon.  The  trans- 
mitter consists  of  a  number  of  carbon  particles  or  granules  in  a 
proper  receptacle  with  a  means  of  varying  the  pressure  upon  the 
granules  in  circuit  with  a  battery  and  the  coarse-wire  winding  of  an 
induction  coil.  The  induction  coil  consists  of  a  bundle  of  soft-iron 
wires,  surrounded  by  two  windings  of  insulated  copper  wire,  one 
being  of  coarse  wire,  with  few  turns  and  low  resistance,  called  the 
"primary."  and  the  other  of  fine  wire,  with  a  large  number  of  turns 
and  higher  resistance,  called  the  "secondary."  The  relative  position 
of  these  various  parts  of  a  local  battery  instrument  is  indicated  in 
figure'  3,  in  which  T  is  the  transmitter  that  contains  the  carbon 
granules  through  which  the  current  from  battery  B  flows.  T  also 
contains  a  diaphragm  which  presses  on  the  carbon  granules,  or  is  so 
connected  with  them  as  to  vary  the  pressure  between  the  particles 
as  the  sound  waves  fall  on  it.  P  is  the  coarse  and  S  the  fine  wire 
winding  of  the  induction  coil  which  is  connected  to  the  receiver  R 
and  the  line.  The  local  battery  circuit  includes  B,  P,  H,  and  T. 


FIG.    3.— SIMPLIFIED   LOCAL    BATTERY   TELEPHONE    CIRCUIT 

As  the  air  vibrations  fall  on  the  diaphragm  at  T  they  produce  a 
change  in  the  resistance  between  the  carbon  particles  in  contact 
with  it.  This  change  of  resistance  causes  the  current  flowing  in 
the  coarse-wire  coil  to  fluctuate,  thereby  inducing  an  alternating 
current  in  the  fine-wire  coil,  which  goes  to  the  line  and  receiver 
and  reproduces  speech,  as  has  been  explained  before. 

COMMON    BATTERY    TRANSMISSION 

The  common   battery   telephone   operates   similarly  to   the   local 
battery    telephone    in    its    essential    details.      The    principal    point 


268 


MILITARY  SIGNAL  CORPS  MAXUAL 


of  difference  lies  in  the  fact  that  in  common  battery  operation  the 
current  which  flows  through  the  transmitter  is  furnished  by  battery 
installed  at  the  central  exchange  in  place  of  local  battery  installed 
in  the  instrument,  as  in  the  case  of  the  local  battery  telephone. 
In  the  common  battery  telephone,  battery  is  supplied  over  the  same 
wires  that  are  used  for  transmitting  speech.  Figure  4  shows  most 
of  the  essential  parts  of  the  common  battery  instrument.  The  in- 
duction coil  for  this  type  of  instrument  is  usually  provided  with 
primary  and  secondary  windings  having  more  nearly  the  same  num- 
ber of  turns  and  resistance  than  is  found  in  the  local  battery  instru- 
ment. The  receiver  and  transmitter  are  practically  identical  with 
.similar  parts  of  the  local  battery  telephone.  The  operation  of  a 
typical  set  is  as  follows  (referring  to  Fig.  4)  : 


FIG.  4.-COMMON  BATTERY   TELEPHONE  CIRCUITS,   SIMPLIFIED 

Direct  current  from  the  positive  side  of  the  battery  at  the  central 
exchange  enters  the  instrument  over  the  line  L,,2  passes  through 
the  hook  H,  primary  winding  P  of  the  induction  coil,  transmitter  T. 
and  leaves  the  instrument  by  the  line  L1.  If  the  transmitter  T 
is  spoken  into,  the  diaphragm,  vibrating,  produces  a  change  in  the 
resistance  between  the  carbon  particles  placed  near  it.  This 
varying  resistance  causes  a  corresponding  variation  in  the  current 
flowing,  which  is  received  at  the  distant  station  as  speech.  This 
varying  current  in  the  winding  P  acting  upon  the  winding  S,  which 
is  placed  upon  the  same  core,  induces  a  current  in  the  receiver 
circuit  composed  of  the  receiver  R  and  the  winding  S.  In  the  case 
of  receiving  from  a  distant  station  the  voice  current  may  be  con- 
sidered to  follow  the  same  course  as  that  taken  by  the  battery 


269 


current.  This  current,  however,  is  variable,  and  in  passing  through 
the  winding  P  of  the  induction  coil  induces  a  current  in  the 
receiver  circuit. 

In  the  normal  condition  of  the  instrument  when  not  in  use  the 
receiver  R  draws  down  the  hook  H,  opening  the  contact,  thus  pre- 
venting the  flow  of  battery  when  the  instrument  is  not  in  use. 

Owing  to  the  fact  that  the  common  battery  instrument  depends 
for  its  operation  on  direct  current  in  the  line,  the  range  of  such 
operation  is  necessarily  limited  by  the  resistance  of  the  line  circuit. 
When  the  resistance  of  the  line  becomes  so  high  as  to  materially  cut 
down  the  strength  of  current,  loudness  of  voice  waves  transmitted  is 
correspondingly  decreased. 

MAGNETO 

The  magneto  generator  is  largely  used  for  producing  the  calling 
current.  It  is  the  simplest  form  of  electric  dynamo  and  consists  of 
an  armature  wound  with  many  turns  of  fine  wire  so  mounted  as  to 
enable  it  to  be  rapidly  revolved  between  the  poles  of  a  permanent 
horseshoe  magnet.  Its  theory  depends  upon  the  principle  that  if  the 
number  of  lines  of  force  passing  through  a  closed  coil  be  varied  a 
difference  of  potential  will  be  developed  between  the  terminals  of 
this  coil,  and  if  an  external  circuit  be  connected  electric  current 
will  flow,  the  direction  of  which  will  depend  upon  the  relative 
direction  of  the  lines  of  force  and  the  movement  of  the  coil. 


C  D 

FIG.   5.— THEORY   OF   TELEPHONE   MAGNETO   GENERATOR 

The  following  from  '"Telephonology,"  by  Van  Deventer,  clearly 
explains  the  action  of  the  magneto  generator : 

A  magneto  generator  is  shown  in  theory  in  figure  5.  A'.  .V. 
represents  ends  of  the  permanent  magnets.  The  center  opening  is 


270  MILITARY  SIGXAL  CORPS  MAXL'AL 

known  as  the  "field."  In  this  is  placed  the  revolving  armature  upon 
which  is  wound  many  turns  of  insulated  wire.  The  manner  in 
which  the  current  is  generated  will  be  understood  from  a  careful 
study  of  the  figures. 

Magnetic  lines  of  force  are  flowing  across  the  field  from  the 
N  to  the  S  pole.  To  generate  a  current  the  wire  must  move  across 
the  lines  of  force,  and  in  A  the  maximum  number  of  lines  are 
passing  through  the  coil.  The  number  of  lines  does  not  change  until 
the  armature  has  passed  beyond  the  position  shown  in  B  and  the 
voltage  is  0.  A  little  beyond  B  the  lines  begin  to  decrease,  and 
current  is  generated  until  C  is  reached,  when  the  remaining  lines 
are  shortened  out  of  the  coil  and  the  rate  of  change  of  the  lines  is 
greatest  and  the  voltage  is  at  a  maximum.  This  is  the  peak  or 
highest  point  of  the  wave,  shown  in  figure  6. 

When  the  position  shown  in  D  is  reached  the  lines  of  force  pass 
through  the  coil  in  the  opposite  direction  and  the  voltage  drops  to 
0.  This  continues  as  long  as  the  crank  is  turned. 

While  the  wire  is  passing  from  the  position  of  A  to  that  of  B 
a  plus  current,  or,  as  it  is  termed,  a  positive  current,  is  generated 
if  the  north  pole  of  the  magnet  is  on  that  side,  while  from  that  in 
C  to  D  a.  minus  or  negative  current  is  generated,  because  the  wire 
is  there  subject  to  the  influence  of  the  south  pole. 

Plus  current  is  represented  by  the  sign  +  and  minus  current 
by  the  sign  — .  Current  flowing  first  in  one  direction  and  then  in 
another  is  called  alternating  current,  and  figure  6  illustrates  waves 


80- 
6O- 

•40- 
<0  20- 
b.6- 


X 


\ 

40 * 


« \   -^  iia£ 


80- 


FIG.  6.— VOLTAGE  CURVE  OF  TELEPHONE  MAGNETO 

of  a  current  of  this  kind  given  by  a  magneto  generator.  On  the 
left  are  figures  representing  the  voltage,  while  the  points  O,  1,  2, 
etc.,  along  the  curved  lines  represent  the  different  positions  of  the 
wire  during  one  revolution  and  correspond  to  those  in  figure  5. 
Starting  at  line  O  where  there  is  no  current,  we  will  suppose  that 
the  upper  curved  line  represents  plus  current  and  the  lower  curved 


THE  CAMP  TELEPHONE 


271 


line  minus  current.  From  this  it  will  be  seen  that  current  from  the 
telephone  generator  flows  first  in  one  direction  and  then  the  other, 
the  voltage  increasing  from  0  to  1,  and  then. decreasing  to  2,  as  the 
wire  at  this  point  (see  B,  Fig.  5)  is  no  longer  cutting  across  the 
lines  of  force.  The  current  then  increases  to  3  in  the  opposite 
direction  (see  C,  Fig.  5),  and  again  decreases  to  0  (D  Fig.  5). 

Magneto  generators  used  hy  the  Signal  Corps  are  provided  with 
an  automatic  device  which  opens  the  armature  circuit  when  the 
armature  is  at  rest. 


FIG.  7.— TELEPHONE  MAGNETO  GENERATOR 

At  the  usual  rate  of  turning  the  magneto  generator  by  hand  the 
voltage  will  be  about  65  to  75  and  the  frequency  about  15  complete 
cycles,  or  30  alternations,  per  second. 


272 


MILITARY  SIGNAL  CORPS  MANUAL 


m 


FIG.   8.-TELEPHONE  HAND   RECEIVER 

In  figure  7,  A  shows  the  generator  armature  on  which  are  wound 
the  many  turns  of  fine  wire  which  are  revolved  in  the  magnetic 
field  referred  to.  It  will  be  noted  that  this  armature  is  made  of 
a  large  number  of  thin  stamped  metal  pieces  which  are  assembled 
on  the  armature  shaft  as  shown.  In  part  B  of  this  figure  the  gen- 
erator armature,  wound,  has  been  placed  within  the  generator 
frame.  Contact  pieces  of  the  device  for  closing  the  generator  cir- 
cuit, mounted  in  place  on  end  of  the  generator  frame,  arft  shown  in 
the  figure.  On  the  other  end  a  gear  which  meshes  with  a  small 
pinion  on  armature  shaft  and  a  crank  for  revolving  are  shown. 
When  crank  is  rotated  in  clockwise  direction,  the  shaft,  upon  which 
is  mounted  the  gear,  automatically  protrudes  through  end  of  frame, 
thereby  closing  the  two  contact  pieces  which  automatically  open 
when  revolving  of  crank  ceases. 

C  shows  a  complete  generator  of  the  5-bar  type,  with  horseshoe 
magnets  in  place. 

Generators  used  by  the  Signal  Corps  are  provided  with  3,  4,  or 
5  bars,  depending  upon  the  class  of  service  in  which  they  are  to 
be  used. 

RECEIVER 

A  hand  receiver  of  the  type  now  used  in  the  Signal  Corps  is 
shown  in  figure  8. 

It  consists  of  a  U-shaped  permanent  magnet  t,  to  the  ends  of 
which  are  fastened  soft-iron  pole  pieces  p  p.  Over  each  pole  piece 
is  a  coil  of  fine  wire  wound  on  a  bobbin  with  nonmagnetic  metal 
heads.  These  coils  are  connected  in  series  in  such  a  manner  as  to 
make  the  front  end  of  one  the  north  pole  and  the  similar  end  of 
the  other  the  south  pole  when  current  flows  through  both  coils  in 


THE  CAMP  TELEPHONE  273 

a  certain  direction.  The  combined  resistance  of  these  coils  con- 
nected in  series  is  about  80  ohms.  The  pole  pieces  pass  through 
the  bottom  of  a  metal  cup  c,  which  is  thus  secured  firmly  in  place. 
The  diaphragm  d,  of  soft  iron,  tinned  or  enameled,  rests  on  the 
rim  of  this  cup.  A  clamping  ring  /  screws  on  the  metal  cup  c, 
thus  holding  the  diaphragm  d  firmly  in  place.  The  receiver  cords 
are  connected  to  terminals  m,  a  strain  cord  being  attached  to  the 
loop  of  the  magnet  to  provide  against  injury  to  the  cord  conductors. 
As  thus  assembled  the  receiver  is  operative  and  may  be  so  used 
in  case  of  accident  to  the  containing  shell  and  cap.  This  shell 
s  slips  over  the  working  parts  of  the  receiver  and  is  held  in  place 
by  the  earpiece  g,  which  screws  on  the  shell.  The  separation  of 
the  diaphragm  from  the  pole  piece  varies  with  the  different  types 
of  receivers,  the  usual  separation  being  about  0.014  inch. 

The  operation  of  the  receiver  is  as  follows : 

The  pole  pieces  pp,  being  attached  to  the  ends  of  the  permanent 
magnet  /,  have  one  a  north  and  the  other  a  south  polarity,  and  the 
magnetic  circuit  is  completed  from  one  pole  to  the  other  through 
the  soft  iron  diaphragm  d,  which  is,  therefore,  drawn  toward  the 
poles  and  held  in  constant  tension.  If  a  current  flows  through  the 
coils  in  such  a  direction  that  the  lines  of  force  due  to  it  coincide 
.with  those  of  the  permanent  magnet,  the  diaphragm  will  be  pulled 
closer  to  the  pole  pieces,  due  to  the  increased  strength  of  the  mag- 
netic field.  If  the  current  flows  in  the  opposite  direction,  the 
strength  of  the  magnetic  field,  due  to  the  permanent  magnet,  will 
be  reduced  and  the  diaphragm  will  spring  farther  from  the  poles. 
It  will  thus  be  seen  that  whether  the  lines  of  force  due  to  the  cur- 
rent in  the  coils  assist  or  oppose  those  due  to  the  permanent  mag- 
net, a  varying  pull  is  produced  on  the  diaphragm  that  causes  vibra- 
tions in  the  latter  in  unison  with  the  changes  in  current.  The  move- 
ment of  the  diaphragm  will  thus  set  up  vibrations  in  the  surround- 
ing air  which  may  be  perceived  as  sound. 

TRANSMITTER 

The  operation  of  the  transmitter  depends  on  the  fact  that  the 
electrical  resistance  between  two  or  more  bodies,  either  in  light  or 
loose  contact,  varies  with  changes  in  the  pressure  between  the 
bodies.  The  change  in  resistance  is  due  to  variation  in  the  area 
of  contact  surface  between  the.granules  and  electrodes  and  not  to 
compression  of  the  carbon  granules  themselves.  In  general,  the 
transmitters  used  by  the  Signal  Corps  depend  on  this  principle.  A 
typical  transmitter  is  shown  in  figure  9.  A  metal  cup,  A,  forms 
the  front  electrode  and  is  attached  to  the  diaphragm  for  sending. 
The  rear  electrode  is  held  rigidly  in  a  metal  bridge  piece,  F,  which 
is  in  turn  fastened  to  the  frame  which  supports  the  mouthpiece  G, 
and  the  remainder  of  the  transmitter.  This  rear  electrode  consists 


274 


MILITARY  SIGNAL  CORPS  MANUAL 


of  a  hard,  polished,  carbon  button,  M,  secured  to  a  brass  button 
between  two  parts  of  which  is  clamped  a  mica  ring  or  diaphragm, 
O,  the  outer  edge  of  which  is  clamped  against  the  front  electrode, 
A,  by  means  of  a  metal  ring,  5",  which  screws  over  A.  The  space 
between  the  front  and  rear  electrodes  is  partly  filled  with  hard 
granular  carbon  of  uniform  size.  Two  dampening  springs,  B  and 
C,  are  provided  to  prevent  vibration  of  the  diaphragm  at  its  natural 
period. 


FIG.  9.— TELEPHONE  TRANSMITTER 

The  operation  of  the  transmitter  is  as  follows: 

Current  from  a  battery  passes  from  one  terminal,  E,  to  the  car- 
bon electrode  through  the  granular  carbon  to  the  metal  cup  which 
forms  the  other  electrode.  If  the  transmitter  now  be  spoken  into, 
the  diaphragm  and  cup  vibrate  in  unison  with  the  sound  waves 
produced  in  the  air,  thus  causing  the  pressure  between  the  front 
and  rear  electrodes  on  the  granular  carbon  to  vary  and  thus  change 
the  resistance  of  the  transmitter.  Therefore,  variations  in  the  cur- 
rent are  set  up  which  correspond  exactly  with  the  voice  vibrations 
which  reach  the  transmitter  diaphragm. 

RINGER 

The  magneto  generator  is  commonly  used  in  connection  with  a 
polarized  bell,  or  ringer,  as  it  is  usually  called,  by  means  of  which 
audible  signals  indicate  the  incoming  calls  on  the  telephone  instru- 
ments. The  usual  form  of  this  piece  of  apparatus  is  shown  in 
figure  10.  In  this  figure  c  c  represents  soft-iron  cores  upon  which 
are  wound  coils  of  fine  wire  connected  in  series  with  the  line  wires 
/  /*.  N  5"  is  a  permanent  magnet,  and  A  a  soft-iron  armature  piv- 
oted at  its  center.  A  slender  rod  terminating  in  a  small  metal  ball 
is  attached  to  the  center  of  the  armature.  When  no  current  is 
flowing  through  the  coil  the  permanent  magnet  N  S  causes  the 


THE  CAMP  TELEPHONE 


275 


upper  ends  of  the  cores  to  be  north  poles  and  the  opposite  ends 
to  be  south  poles.  In  this  condition  the  armature  will  be  attracted 
by  both  cores  and  will  rest  against  one  or  the  other,  as  may  chance 
to  happen.  If  current  passes  through  the  coils  in  series  in  such 
direction  as  to  increase  the  strength  of  the  north  pole  /,  and  to 
make  e  south  pole  or  weaker  north  pole,  then  /  will  attract  the  end 


FIG.   10.— TELEPHONE  RINGER 

of  the  armature  opposite  it,  while  c  will  repel  this  end  of  the  arma- 
ture or  attract  it  with  smaller  force.  If  the  current  is  now  reversed 
in  direction  so  that  /  becomes  a  south  pole  or  a  weaker  north  pole 
and  c  a  stronger  north  pole,  the  action  will  be  reversed,  c  will  at- 
tract its  end  of  the  armature  and  /  repel  its  end  or  attract  it  with 
smaller  force.  With  the  ringer  connected  to  the  magneto  generator 
as  shown  in  this  figure,  the  armature  will  vibrate  between  the  two 
gongs  with  the  same  frequency  as  the  current  produced  by  the  hand 
generator,  and  a  practically  continuous  ringing  sound  will  result. 
Practically  all  of  the  ringers  used  by  the  Signal  Corps  are  wound 
to  a  resistance  of  1,000  ohms. 

TYPES  OF  INSTRUMENTS 

The  principles  upon  which  depends  the  operation  of  the  various 
parts  of  the  telephones  have  been  explained  in  the  preceding  pages. 


27o 


Ml  LIT.  IKY  S1CX.IL  CORPS  MAXUAL 


The  complete  circuits  of  the  instruments  of  the  various  types  used 
by  the  Signal  Corps  will  now  be  considered,  and  it  will  be  assumed 
that  the  operation  of  the  various  parts  as  just  explained  is  under- 
stood, and  will  not  be  discussed  further.  The  instruments  to  be 
described  have  been  selected  as  being  typical  of  those  now  in  use, 
and  while  slight  modifications  of  the  circuits  shown  may  be  en- 
countered it  is  believed  that  if  a  person  familiarizes  himself  with 
these  circuits  no  trouble  will  be  experienced  in  mastering  any  which 
are  slightly  different. 

It  will  be  noted  that  desk  telephones  of  local  battery  and  com- 
mon battery  types  employ  precisely  the  same  principles  as  wall 
telephones,  but  that  it  is  necessary  to  modify  circuits  and  relative 
positions  of  component  parts  in  order  to  meet  requirements  whereby 
the  ringer  (and  magneto  generator  in  local  battery  instruments) 
are  stationary  and  the  transmitter,  receiver,  and  hook  switch  (as  a 
unit)  are  movable.  To  accomplish  this,  all  manufacturers  employ 
the  well-known  desk  stand  and  ringer  box,  connecting  the  two  by 
means  of  a  flexible  cord  consisting  of  two  or  more  conductors. 
Some  manufacturers  place  the  induction  coil  in  the  ringer  box  and 
others  in  the  base  of  the  desk  stand. 

Circuits  of  the  local  battery  telephone  are  as  follows,  reference 
being  made  to  figure  11. 


FIG.    11. -CIRCUITS    OF    LOCAL    BATTERY    TELEPHONE 

Being  Called. — Hook  switch  contacts  shown  in  diagram  as  closed 
would  be  open,  as  receiver  would  not  be  removed  from  hook  of 
hook  switch.  Magneto  generator  current  enters  at  L,  to  ringer, 
to  L\ 

Calling  Distant  Station. — Hook  switch  contacts  shown  in  dia- 
gram as  closed  would,  be  open,  as  receiver  would  not  be  removed 
from  hook  of  hook  switch.  Revolving  crank  of  magneto  generator 


THE  C.-IMT   ll-Ll-rilOXE  277 

contact  at  C  is  closed  and  circuit  is  C  to  L.  through  one  side  of 
line,  to  ringer  of  distant  station,  through  other  side  of  line.  L1  to  A. 

It  will  be  noted  that  ringer  of  station  calling  will  also  be  op- 
erated. The  reader  will  bear  in  mind  that  the  windings  of  ringers 
are  of  high  impedance,  which,  as  previously  explained,  offers  a  very 
high  resistance  to  the  high  frequency  alternating  currents  trans- 
mitting the  sound  waves,  and  for  this  reason  they  can  be  connected 
direct  across  the  line.  The  magneto  generators  are  capable  of  op- 
erating forcibly  under  usual  line  conditions  approximately  ten 
ringers. 

Listening. — Hook-switch  contacts  are  closed  as  shown  in  dia- 
gram, as  receiver  should  be  removed  from  hook.  A  high  voltage, 
high  frequency  alternating  current  from  distant  telephone  enters  at 
L,  passes  through  receiver,  secondary  of  induction  coil,  contact  1. 
hook  of  hook  switch,  and  L1. 

Talking. — Hook  switch  contacts  are  closed,  as  shown  in  dia- 
gram, as  receiver  would  be  removed  from  hook.  Direct  current 
flows  in  primary  circuit  as  follows :  Battery,  transmitter,  contact  2, 
hook  of  hook  switch,  contact  1,  primary  of  induction  coil.  Voice 
waves  fall  on  diaphragm  of  transmitter,  varying  strength  of  cur- 
rent in  primary  circuit,  thereby  inducing  in  secondary  of  induction 
coil  a  high  voltage  and  high  frequency  alternating  current  which  is 
transmitted  to  distant  receiver  by  means  of  the  following  circuit  : 
Secondary  of  induction  coil,  contact  1  of  hook  switch,  hook  switch, 
L1,  one  side  of  line,  circuit  of  distant  telephone,  other  side  of  line, 
L,  receiver,  connection  to  induction  coil. 

A  few  commercial  standard  local  battery  telephones  are  shown 
in  figures  12  to  15  which  follow: 

LOCAL  BATTERY  WALL  TELEPHONE 

The  circuits  of  the  local  battery  wall  telephone  of  the  Sumter 
Telephone  Manufacturing  Co.'s  make  are  shown  in  Figure  12. 

This  figure  indicates  the  actual  wiring  of  the  instrument  and 
the  parts  correctly  placed  with  relation  to  each  other  as  they  are 
mounted  in  the  instrument.  The  circuits  of  this  instrument  may 
be  traced  as  follows  : 

1.  Incoming  signals  enter  at  line  L1,  pass  to  hinge  C,  to  bell  B, 
to  hinge  C1,  and  return  to  line  L.     The  hook  switch  is  shown  in 
its   normal   position   with   the  hand   receiver   in   place,   all    contacts 
being  open. 

2.  Outgoing  signals  pass  from  one  pole  of  the  generator  G  to  the 
line  L,  through  the  distant  instrument  and  return  on  L1  to  hinge  C, 
to  the  opposite  pole  of  the  generator   G.     In   this  instrument  the 
bells   B   are   permanently   connected   between    the   lines   L  and   L1, 
as  is  also  the  generator  G.     The  latter,  however,  by  means  of  its 
switching  device,  is  open  circuited  when  not  in  operation. 


278 


MIUTARV  S1GX.IL  CORl'S  MANUAL 


FIG.   12— SUMTER  LOCAL  BATTERY  WALL  TELEPHONE 
AXD    CIRCUITS 

Key  to  reference  numbers: — 1,  backboard;  2,  hinged  shelf;  3,  transmitter;  4, 
transmitter  mouthpiece;  5,  transmitter  bracket;  6,  bracket  arm;  7,  hand 
receiver;  8,  cord  of  hand  receiver;  9,  binding  post  line;  10,  gong  for 
ringer;  11,  hook  for  switch;  12,  magneto  crank  handle. 


3.  The  local  battery  and  transmitter  circuits  pass  from  the  bat- 
tery through  the  transmitter  and  the  coarse-wire  winding  of  the 
induction  coil  through  the  hook-switch  H,  which  now  has  all  con- 
tacts closed,  to  the  opposite  pole  of  the  battery.  The  receiving  cir- 
cuit passes  from  L1  to  the  hook  switch  H,  through  the  fine-wire 
winding  of  the  induction  coil,  through  the  receiver  R,  to  the  line  L. 

LOCAL  BATTERY  DESK  SET 

In  figure  13  is  shown  circuits  of  the  local  battery  desk  telephone 
of  the  Sumter  make,  as  furnished  to  the  Signal  Corps.  The  usual 
bridging  circuit  is  used.  The  diagram  shows  the  actual  wiring  as 


THE  CAMP  TELEPHONE 


279 


it  is  found  in  the  instrument,  and  the  various  parts  are  shown  cor- 
rectly placed  with  respect  to  each  other. 


L2 


FIG.  14.-CIRCUITS  OF  GARFORD  LOCAL  BATTERY  WALL  TELEPHONE 

The  wiring  of  the  Garford  local  battery  wall  telephone,  which 
is  furnished  by  the  Signal  Corps  is  shown  in  figure  14.  In  this 
figure,  A  shows  a  simplified  circuit,  and  B  the  wiring  as  actually 
found  in  the  instrument  with  the  parts  correctly  located  with  re- 
spect to  each  other. 

Figure  15  shows  the  Garford  local  battery  desk  telephone  and 
the  circuits  employed  with  this  instrument. 


280 


MILITARY  SIGNAL  CORPS  MANUAL 


FIG.    13.— CIRCUITS    OF    SUMTER    DESK    LOCAL    BATTERY 
DESK   TELEPHONE 


FIG.  15.— GARFORD  LOCAL  BATTERY  DESK  TELEPHONE. 
Key  to  reference  _  numbers: — 1,  ringer_box;  2,  door  for  ringer  box;  3,  screw 
fastener  for  ringer  box;  4,  line  binding  post;  5,  gong;  6,  hammer  and 
armature;  7,  magneto  crank  handle;  8,  desk  stand;  9.  switch  hook;  10. 
transmitter;  11.  transmitter  mouthpiece;  12,  hand  receiver;  13,  shell  for 
receiver  cap;  15,  main  cord 


THE  CAMP  TELEPHONE 
COMMON  BATTERY  TELEPHONE 


281 


In  general  it  may  be  said  that  the  parts  used  in  the  common  bat- 
tery wall  telephones  are  similar  to  those  used  in  the  local  battery. 

It  will  usually  be  found  that  the  primary  of  the  induction  coil 
used  in  the  common  battery  instruments  is  of  higher  resistance,  and 
that  the  ratio  between  the  primary  and  secondary  windings  of  the 
induction  coils  are  quite  different.  The  distinguishing  difference 
between  the  commercial  local  battery  telephone  and  common  battery 
telephone  is  that  the  comtpon  battery  instrument  is  not  equipped 
with  a  magneto  generator  for  calling,  or  batteries  for  furnishing 
current  for  transmitting  sound  waves,  and  is  equipped  with  a  con- 


LINC    BINDING   POSTS 


INDUCTION 


FIG.  16.-CIRCUITS  OF  WESTERN  ELECTRIC  CO.   COMMON  BATTERY 
WALL    TELEPHONE 

denser  in  series  with  the  ringer.  The  secondary  of  induction  coil 
in  the  local  battery  telephone  is  in  series  with  outside  line  and 
receiver  when  receiver  is  removed  from  switch  hook,  while  with 
the  common  battery  instrument  under  similar  conditions  the  sec- 
ondary of  induction  coil  is  in  series  with  receiver,  transmitter  and 
condenser,  the  primary  of  induction  coil  being  in  series  wjth  trans- 
mitter and  outside  line.  By  reference  to  figure  16,  which  shows 
circuits  of  the  common  battery  telephone,  it  will  be  noted  that  the 
paths  of  both  the  current  in  primary  of  induction  coil  and  current 


282 


MILITARY  SIGNAL  CORPS  MANUAL 


in  secondary  of  induction  coil  traverse  the  same  line  through  trans- 
mitter. They  do  not  interfere  with  each  other  in  any  way,  and 
the  transmitter,  being  of  low  ohmic  resistance  and  practically  zero 
impedance,  offers  comparatively  no  resistance  to  either. 

The  reason  for  this  rearrangement  of  component  parts  is  due 
to  the  fact  that  battery  for  furnishing  necessary  current  for  opera- 
tion is  remote  from  location  of  telephone  and  is  conducted  to  in- 
strument by  means  of  the  line  wires.  The  battery  usually  consists 
of  12  or  15  cells  of  storage  battery  having  a  voltage  of  24  or  30. 
respectively.  •• 

While  the  ohmic  resistance  of  the  ringer  is  comparatively  high, 
usually  being  1,000  ohms,  it  will  be  seen  that  by  connecting  this 
direct  across  the  line  a  considerable  waste  of  current  would  ensue, 


THEORY 


B 


FIG.    17.— CIRCUITS  OF   SUMTER   COMMON   BATTERY 
WALL    TELEPHONE 

consequently  the  condenser  which  opens  the  direct  current  circuit 
is  placed  in  series  with  the  ringer  across  the  line.  Another  reason 
for  this  condenser  is  that  with  the  commercial  eommon  battery 


THE  CAMP   TELEPHONE 


28.3 


telephone  the  operator  at  switchboard  is  signaled  by  merely  remov- 
ing receiver  from  hook,  thereby  closing  the  direct  current  circuit 
through  a  magnetic  device  at  switchboard.  The  devices  are  ordin- 
arily of  200  ohms  resistance  and  operate  on  approximately  0.01  of 
an  ampere  of  current,  so  that  by  referring  to  Ohm's  law  in  another 
chapter  the  reader  can  readily  determine  that  this  signal  would  be 
held  closed  if  the  1,000-ohm  ringer  were  connected  directly  across 
the  ordina  y  line  without  condenser  in  series. 

A  few  commercial  standard  common  battery  telephones  are 
shown  in  figures  17  to  22. 

The  circuits  of  the  common  battery  wall  telephone  of  the  Sum- 
ter  Manufacturing  Co.  are  shown  in  figure  17.  A  shows  the  wiring 
of  the  instrument  and  the  parts  with  correct  relation  to  each  other, 


FIG.  18.— COMMON  BATTERY  DESK  TELEPHONE 

and  B  a  simplified  circuit  diagram  of  the  instrument.     The  opera- 
tion of  the  instrument  is  as   follows: 

Assuming  that  the  receiver  is  in  place  on  the  hook  switch,  the 
incoming   ringing   current   will   pass   from   the   line  L1   through   the 


284 


MILITARY  SIGNAL  CORPS  MANUAL 


FIG.  19.-COMMON  BATTERY  WAIX  TELEPHONE 

Key  to  reference  numbers: — 1,  line  binding  post;  2,  induction  coil;  3,  induc- 
tion coil  terminals;  4,  condenser;  5,  hook;  8,  shell  for  receiver;  9, 
ringer 


THE  CAMP   TELEPHONE 


285 


hflls  B,  condenser  C,  to  the  line  L,  ringing  the  bells  R.  The  hand 
receiver  being  removed  from  the  hook  switch,  the  contacts  at  H 
are  closed.  In  this  condition  the  battery  from  the  central  exchange 
passes  from  Ll  through  the  coarse-wire  winding  of  the  induction 
coil,  through  the  transmitter  to  the  line  L.  Battery  also  passes 
from  the  bells  B,  secondary  or  fine-wire  winding  of  the  induction 
coil,  receiver  R,  transmitter  T,  to  the  line  L.  The  resistance  of 
this  second  path  is  very  much  greater  than  that  of  the  first  path, 
so  that  the  current  flowing  in  this  high  resistance  path  may  be  con- 
sidered negligible.  If  the  transmitter  be  spoken  into,  the  current 
flowing  through  the  transmitter  will  vary  by  reason  of  the  varying 
resistance  of  the  transmitter  caused  by  varying  pressure  between 
the  carbon  granules.  These  fluctuations  in  current  result  in  a  fluc- 


FIG.   20.-CIRCUITS  OF  NORTH   ELECTRIC  CO.   COMMON   BATTERY 
WALL    TELEPHONE 

tuating  current  in  the  primary  of  induction  coil  in  telephone  at  dis- 
tant station  and  induce  in  the  secondary  of  same  induction  coil  a 
high-voltage,  high-frequency  alternating  current  which  affects  the 
receiver,  thereby  reproducing  speech.  Incoming  speech  follows 


286 


MILITARY  SIGNAL  CORPS  MANUAL 


the  same  circuit  as  that  taken  by  the  battery  from  the  central  ex- 
change. This  voice  current,  however,  being  pulsating  in  character, 
induces  a  current  in  the  fine-wire  winding  of  the  induction  coil. 
This  current  passes  through  receiver  R,  hook  switch,  transmitter  T, 


FIG.   21.— CIRCUITS   OF   X.    E.   CO.    COMMOX   BATTERY 
DESK   TELEPHOXE 

and  condenser  C,  thus  reproducing  in  the  receiver  R  the  sounds 
impressed  on  some  distant  transmitter.  The  condenser  also  serves 
to  strengthen  the  effect  of  the  induced  current  in  R  by  reason  of 
the  varying  potential  across  its  terminals. 


THEORY 


BELL  BOX  DESK  STAND 

FIG.  22.— GARFORD  COMMOX   BATTERY  DESK  TELEPHOXE   CIRCUITS 


THE  CAMP  TELEPHONE 


287 


Figure  18  shows  the  general  arrangement  of  a  common  battery 
desk  telephone  and  figure  19  shows  the  general  arrangement  of 
the  common  battery  wall  telephone.  The  circuits  shown  or  modifi- 
cations of  them  are  used  by  all  manufacturers  and  the  general 
appearance  of  the  apparatus  closely  resembles  that  shown  in  the 
illustrations. 

Figure  20  shows  the  circuits  as  installed  of  a  North  Electric  Co. 
C.  B.  wall  telephone.  Figure  21  shows  the  circuits  as  furnished  in 
the  desk  set  type  of  the  same  instrument. 

Figure  22  shows  the  circuits,  as  installed,  of  a  common  battery 
desk  telephone,  having  the  induction  coil  located  in  the  base  of  the 
desk  stand. 

THE  CAMP  TELEPHONE 

This  telephone,  which  supersedes  the  field  telephone,  was  de- 
veloped by  the  Signal  Corps  for  use  in  connection  with  camp  tele- 


FIG.  23.— THE  CAMP  TELEPHONE  AND  ITS  CIRCUITS 

Key  to  reference  numbers: — 1,  case;  2,  hinged  cover;  3,  circuit  diagram 
frame;  4,  circuit  diagram;  5,  metal  base  for  case;  6,  wire  netting  frame; 
7,  wire  netting;  8,  carrying  strap;  9,  fitting  and  ring  for  carrying  strap 


288  MILITARY  SIGNAL  CORPS  MANUAL 

phone  systems  and  small  arms  target  range  system,  and  may  be  in- 
stalled in  tents  and  structures,  or  considered  a  portable  instrument 
for  use  in  the  field  for  testing  lines  or  other  purposes. 

It  is  of  local  battery  type.  The  battery  employed  is  one  unit 
of  tungsten  type  A.  Figures  23  and  24  illustrate  this  telephone,  it 
being  shown  dismantled  in  Figure  24  to  facilitate  identification  of 
parts  in  connection  with  the  preparation  of  requisitions  for  re- 
newals. 

The  first  lot  of  these  instruments  was  equipped  with  2-bar  mag- 
netos and  due  to  its  limitations  the  instrument  could  not  be  used 
for  long-distance  work.  The  new  model  of  this  instrument  will  be 
equipped  with  a  3-bar  magneto,  employing  a  special  high  grade 
steel  for  permanent  magnets,  and  while  in  other  features  there  may 
be  a  slight  deviation  from  the  following  description  it  is  believed 
that  figures  23  and  24  can  be  used  in  preparing  requisitions,  it  be- 
ing merely  necessary  to  state  "For  Camp  Telephone,  3-bar  magneto 
type." 

The  instrument  is  made  as  compact  as  practicable  and  is  con- 
tained in  an  oak  case  4,%  by  7  by  10  inches  high.  The  top  consists 
of  a  metal  hinged  cover  with  circuit  diagram  on  inside,  held  rigid 
when  closed  by  a  spring  snap  which  can  be  released  by  depressing 
a  button.  The  bottom  of  case  is  covered  by  a  flanged  piece  of 
metal,  the  flange  projecting  approximately  one-half  inch  up  sides 
of  case.  Through  one  side  of  the  case  are  six  three-eighth  inch 
holes  which  are  covered  on  the  outside  by  a  close  mesh  metal  screen 
held  in  place  by  a  metal  frame.  These  apertures  allow  the  ringer 
to  be  distinctly  heard.  The  case  is  equipped  with  a  substantial,  ad- 
justable carrying  strap,  each  end  of  which  is  fastened  to  case  by 
means  of  hinged  metal  rings. 

A  small  2-bar  magneto  generator,  small  ringer,  induction  coil, 
aluminum  chamber  for  the  single  unit  of  tungsten  type  A  dry  bat- 
tery, hard  rubber  block  upon  which  are  mounted  line  binding  posts, 
plug  connections  for  the  hand-set  used  with  the  instrument,  hook 
switch  and  hook  operating  it  and  auxiliary  battery  binding  posts  are 
all  mounted  on  a  common  base  which  may  be  readily  removed  from 
case  after  removing  magneto  generator  crank,  metal  housing  for 
it  and  three  screws  which  extend  through  the  case. 

The  instrument  may  be  operated  with  cover  closed,  which  is 
highly  advantageous  in  inclement  weather.  To  accomplish  this 
there  is  a  suitable  opening  for  leading  out  the  3-conductor  cord  to 
receiver  and  transmitter,  the  two  latter  being  mounted  in  the  form 
of  a  unit,  termed  a  hand-set.  This  hand-set  consists  of  a  transmitter 
and  receiver  mounted  on  a  metal  piece  and  is  so  designed  that  when 
the  transmitter  is  normally  placed  to  the  mouth,  the  receiver  is 
automatically  adjusted  to  the  ear. 


THE  CAMP  TELEPHONE 


289 


The  hook  of  the  hook  switch  is  so  designed  that  it  protrudes 
through  case.  When  it  is  desired  to  transport  the  instrument  or 
to  remove  the  base  upon  which  is  mounted  all  the  parts  of  the  in- 
strument, it  is  merely  necessary  to  depress  the  hook  and  push  it 
toward  the  base.  By  this  arrangement  the  hook  is  not  only  held 
in  the  down  position,  thereby  opening  the  battery  circuit,  but  it  is 
also  protected. 

The  aluminum  chamber  for  hqusing  the  single  unit  of  tungsten 
type  A  battery  is  equipped  with  a  spring  catch  so  located  that  when 


FIG.   24.— CAMP  TELEPHONE,   DISMANTLED. 

Key  to  reference  numbers:—!,  base;  2,  connecting  block  with  binding  posts; 
3,  binding  post;  4,  socket  for  hand-set  cord;  5,  hand-set;  6,  hand-set 
cord;  7,  hand-set  receiver;  8,  hand-set  transmitter;  9,  battery  case- 
10,  battery-spring  catch;  11,  battery  spring  and  support;  12,  magneto; 
13,  magneto  crank  handle;  14,  permanent  magnet  for  magneto;  15,  con- 
tact spring;  16,  magneto  gear;  17,  magneto  pinion;  18,  ringer;  19,  gong; 
20,  hammer  and  armature  for  ringer;  21,  ringer  coils;  22,  case  for  hook 
switch;  23,  switch  hook;  24,  binding  posts  for  external  battery 

upper  hinged  piece  is  depressed  to  proper  position  the  battery  com- 
presses a  helical   spring,   thereby   insuring  continual   contact.     The 


290  MILITARY  SIGNAL  CORPS  MANUAL 

base  is  equipped  with  two  screw  binding  posts  which  may  be  used 
to  connect  leads  to  an  outside  battery  in  the  event  of  there  being 
no  tungsten  type  A  batteries  available. 

An  aluminum  frame,  which  is  supported  on  the  base  previously 
mentioned,  forms  a  compartment  for  the  hand-set  when  instrument 
is  being  transported.  When  the  instrument  is  installed  for  a  tem- 
porary period,  unless  in  actual  operation,  the  proper  place  for  the 
hand-set  is  hanging  on  the  hook  of  hook  switch,  there  being  a  ring 
on  the  hand-set  for  this  purpose. 

A  small  screw  driver  which  will  fit  practically  all  screws  used 
in  the  construction  of  the  instrument  is  supported  by  the  metal 
frame  and  is  furnished  with  each  instrument.  The  instrument  com- 
plete weighs  approximately  11  pounds. 

THE  SERVICE  BUZZER 

The  buzzer  is  strictly  a  portable  instrument  and  is  issued  to 
troops  in  the  field  for  use  in  connection  with  all  kinds  of  communi- 
cation. It  may  be  used  as  a  telephone  or  for  sending  Morse  or 
Continental  Code  signals,  and  for  that  reason  it  is  specially  adapted 
for  field  use. 

When  it  becomes  impracticable  to  transmit  messages  telepho- 
nically,  due  to  the  line  becoming  impaired  or  for  other  reasons, 
the  usual  telegraphic  signals  can  be  transmitted  and  are  received 
in  distant  telephone  receivers  in  the  form  of  a  high-pitched  hum, 
somewhat  similar  to  radiotelegraphic  signals.  These  signals  have 
been  exchanged  between  two  of  these  instruments  after  the  wire 
line  had  been  severed,  both  the  ends,  however,  being  slightly 
grounded. 

The  service  buzzer,  which  is  the  latest  approved  instrument  of 
this  type  of  apparatus,  replaces  the  field  buzzer,  the  cavalry  buzzer 
and  the  field  artillery  telephone  and  hereafter  is  the  standard  issue. 

In  the  first  part  of  this  chapter  it  is  explained  how  a  circuit  of 
high  E.  M.  F.  is  obtained  by  means  of  two  coils  of  wire  wound  on 
a  soft  iron  core  in  connection  with  the  telephone.  This  method 
may  be  termed  mutual  induction  and  is  employed  in  the  service 
buzzer.  A  high  E.  M.  F.  can  be  obtained  by  means  of  one  coil  of 
wire  wound  on  a  soft  iron  core,  the  latter  method  being  termed 
self-induction.  In  order  that  operation  of  the  service  burrzer  may 
be  clearly  understood,  the  theory  of  the  field  buzzer  will  first  be 
explained. 

The  principle  upon  which  the  original  field  buzzer  operates  de- 
pends upon  the  effects  of  self-induction,  i.  e.,  the  comparatively  high 
self-induced  voltage  developed  at  the  terminals  of  an  electromagnet 
(coil  with  iron  core)  when  the  current  through  the  circuit  is  sud- 
denly interrupted.  The  interruptions  are  automatically  produced  by 


THE  SERVICE  BUZZER 


291 


a  circuit  breaker,  which  is  described  later.  During  the  interval  ot 
time  required  for  the  current  to  reach  its  maximum  value,  the  field 
of  force  expands  in  direct  proportion  to  the  current  strength  until 
it  also  reaches  maximum  value.  The  current  strength  being  kept 
constant,  the  magnetic  field  is  of  constant  value.  Any  variation  in 
current  strength  produces  a  corresponding  variation  in  the  strength 
of  the  magnetic  field ;  therefore,  when  the  circuit  is  broken  and 
the  current  rapidly  falls  to  zero  the  field  of  force  also  collapses 
and  disappears.  The  energy  furnished  by  the  current  and  stored 
up  in  the  magnetic  field  is  thus  returned  to  the  circuit  and  tends  to 
sustain  the  original  current,  as  is  noticed  by  a  bright  spark  appear- 
ing at  the  point  of  break. 

On  "make,"  then,  the  whirls  spring  out  from  and  cut  the  wire, 
inducing  therein  a  current  opposed  in  direction  to  inducing  cur- 
rent. On  "break"  the  whirls  collapse,  again  cutting  the  wire  and 
inducing  therein  a  current  having  same  direction  as  inducing  cur- 
rent. The  phenomena  resulting  from  such  cutting  of  a  wire  by 
magnetic  lines  of  force  is  called  self-induction. 

When  the  circuit  contains  a  coil,  the  effects  of  self-induction  are 
much  greater.  If  the  coil  contains  an  iron  core  the  effects  of  self- 
induction  are  still  more  pronounced. 

To  make  clear  the  action  of  the  buzzer,  let  us  consider  the  dia- 
gram, figure  25 : 

B  is  a  battery  of  five  dry  cells ;  A'  is  a  key  for  making  and  break- 
ing the  circuit ;  E  an  electromagnet ;  R  a  telephone  receiver. 

When  the  key  is  closed  there  is  a  rush  of  current  which  reaches 
its  maximum  strength  almost  instantly.  Simultaneously  there  is 
built  up  a  magnetic  field  of  force  around  the  electromagnet.  Now, 
if  the  key  be  opened,  a  pronounced  click,  of  momentary  duration, 
is  heard  in  the  receiver,  which  is  caused  by  a  self-induced  current 
of  high  E.  M.  F.  produced  by  the  collapse  of  the  magnetic  field 
around  the  coil.  This  induced  current  would  spark  across  the  break 
at  the  key  if  there  were  not  an  alternate  complete  circuit  through 
the  receiver. 


K 


,  ,             0    1 

E 

R. 

c^ 

jyy/y 

lllllllin 

FIG.    25.— SIMPLIFIED   CIRCUIT   OF    FIELD    BUZZER 


-*)2  MILITARY  SIGNAL  CORPS  MANUAL 

The  more  rapidly  the  circuit  is  made  and  broken  by  closing  and 
opening  the  key,  the  greater  the  rapidity  with  which  clicks  in  tele- 
phone follow  one  another,  until,  if  the  interruptions  recur  suffi- 
ciently often,  the  sounds  in  the  receiver  appear  to  be  almost  con- 
tinuous. 


£ 

B 

i 

M\j 

L 

^ 

ililililiU 

*~A 

FIG.  26.— FIELD   BUZZER   SIMPLIFIED  CIRCUIT  WITH   INTERRUPTER 

If  we  introduce  an  automatic  interrupter  into  the  circuit  (Fig. 
26),  a  loud  buzzing  sound  is  heard  in  the  receiver  whenever  the 
key  is  closed,  and  the  dot  and  dash  of  the  Morse  alphabet  are 
thereby  produced  by  making  short  and  long  contacts  with  key. 

The  action  of  the  interrupter  or  circuit  breaker  is  as  follows : 

When  the  circuit  is  made  by  closing  the  key  K,  the  current  flows 
through  coils  of  the  electromagnet  E,  magnetizing  the  iron  core  M, 
which,  in  turn,  attracts  armature  A.  As  soon  as  the  armature  is 
withdrawn  from  contact  5"  the  circuit  is  broken ;  as  a  result,  the 
core  becomes  demagnetized  and  armature  A  springs  back  against 
S,  thus  again  closing  the  circuit.  The  action  continues  so  long  as 
key  K  is  kept  closed. 

If  instead  of  the  interrupter  we  substitute  therefor  a  transmitter 
(Fig.  27),  then  when  the  key  is  closed  current  flows  from  -f-  side 
of  the  battery  through  the  coil  to  the  lower  disk  (stationary)  of 
transmitter,  through  loosely  packed  carbon  granules  to  upper  disk 
(movable),  which  is  attached  to  the  diaphragm,  to  key,  to  —  side 
of  battery. 


Uppercase                                                ..... 

11  u 

00                          B 

5T        nil    1. 

FIG.   27.— SIMPLIFIED   CIRCUIT  OF   FIELD    BUZZER 
WITH   TRANSMITTER 


THE  SERVICE  BUZZER 


293 


Except  when  this  circuit  is  first  made,  there  is  no  evidence  of 
self-induction  in  the  circuit  until  the  transmitter  is  spoken  into, 
then  the  sound  waves  of  the  voice  striking  the  diaphragm  cause  it 
to  vibrate.  The  carbon  granules  between  the  carbon  disks  are  thus 
subjected  to  varying  pressure;  this  causes  a  variable  resistance  in 
the  circuit,  and  the  resulting  current  is  a  pulsating  one  (uniform  in 
direction,  but  varying  in  strength).  The  effect  of  the  varying  cur- 
rent passing  through  the  circuit  is  to  increase  and  decrease  the 
field  of  force  built  up  around  the  wire.  This  changing  field  of 
force  in  turn  produces  the  effects  of  self-induction,  and  these  ef- 
fects are  particularly  noticeable  in  coil  E. 

The  inductive  property  of  the  coil  is  thus  employed  to  augment 
the  comparatively  weak  primary  current  to  one  of  high  E.  M.  F., 
which  intensifies  the  vibration  of  the  receiver  diaphragm,  these 
vibrations  being  received  by  the  ear  as  articulate  speech. 

The  sounds  thus  produced  are  not  as  loud  as  those  produced  by 
the  interrupter,  even  though  the  same  number  of  cells  are  used,  for 
the  reason  that  in  the  latter  case  the  current  is  completely  inter- 
rupted (circuit  broken),  whereas,  in  the  case  of  the  talking  circuit, 
current  is  always  flowing  but  is  varied  in  strength ;  therefore  the 
resulting  field  of  force  never  reduces  to  zero,  the  cutting  of  the 
wire  is  consequently  less,  and  the  effects  of  self-induction  are 
diminished. 

If  we  now  combine  the  two  circuits  described  in  one  diagram 
we  have  the  simplified  buzzer  diagram  which  is  shown  in  Fig.  28. 

An  examination  of  this  figure  shows  that  the  only  change  made 
is  the  introduction  of  two  terminal  binding  posts,  one  of  which  is 
connected  to  the  line,  the  other  to  the  ground.  If  a  similar  instru- 
ment is  connected  at  the  distant  stations,  the  currents  traversing  the 
home  receiver  also  pass  through  the  distant  receiver. 


FIG.    28.— SIMPLIFIED   CIRCUIT   OF   FIELD   BUZZER   WITH 
TRANSMITTER     AND    INTERRUPTER 


294 


MILITARY  SIGNAL  CORPS  MAXVAL 


The  utilization  of  existing  telegraph  lines  as  a  part  or  the  whole 
of  a  circuit  for  buzzer  and  telephone  working,  at  the  same  time 
not  interfering  with  the  use  of  the  wire  for  Morse  working,  may 
be  effected  by  using  condensers  interposed  between  the  line  and 
the  buzzer.  See  Fig.  29. 

Telegraph  Line 


FIG.   29.— BUZZERS   CONNECTED  TO  A   TELEGRAPH   LINE 

The  pulsations  of  the  ordinary  Morse  sending  are  comparatively 
slow.  The  condensers,  therefore,  act  as  a  very  large  resistance,  and 
no  appreciable  effect  will  be  noticed  in  the  telegraph  line. 

The  very  rapid  pulsations  produced  by  the  buzzer  or  transmit- 
ter, however,  will  permit  of  transmission  from  one  buzzer  to  the 
other  with  little  diminution  of  sound. 

Figure  30  shows  the  circuits  of  the  service  buzzer.  It  will  be 
noted  that  with  the  field  buzzer  if  a  line  of  low  insulation  resistance 
is  utilized  a  heavy  drain  on  the  battery  will  ensue,  due  to  the  bat- 
tery being  connected  to  the  line,  while  with  the  service  buzzer  un- 
der like  conditions  a  heavy  drain  will  not  exist,  due  to  the  battery 
being  connected  in  a  local  circuit  which  does  not  physically  connect 
with  the  line.  It  will  also  be  noted  that  a  condenser  which  can  be 
cut  out  by  means  of  a  short-circuiting  switch  is  contained  in  the 
instrument  and  connected  in  series  with  the  line.  This  condenser 
is  for  use  when  it  is  desired  to  use  an  existing  telegraph  line.  (See 
Fig.  29.)  Two  units  of  tungsten  type  A  dry  battery  are  used  with 
the  service  buzzer  for  furnishing  the  necessary  primary  current, 
both  being  in  circuit  when  sending  telegraphic  signals,  and  one  only 
being  in  transmitter  circuit  for  telephone  communication. 

The  circuits  of  the  service  buzzer  may  be  classed  as  follows: 

Primary  sending  circuit — telegraph. 

Secondary    sending    circuit — telegraph. 

Receiving  circuit — telegraph. 

Primary    sending    circuit — telephone. 

Secondary    sending   circuit — telephone. 

Receiving  circuit — telephone. 


THE  SERVICE  BUZZER 


295 


These  circuits  may  be  traced  as  follows,  reference  being  made 
to  figure  30: 

Primary   Sending   Circuit — Telegraph 

S.  P.  D.  T.  knife  switch  marked  "Sw"  must  be  closed  on  side 
marked  "buzzer."  Upon  depressing  key  K,  circuit  is  as  follows : 
Positive  end  of  battery,  through  primary  of  induction  coil,  to  A  to 
B,  contact  1  of  key,  lever  of  key,  contact  2,  vibrator,  to  negative 
end  of  battery. 

Secondary  Sending  Circuit— Telegraph 

S.  P.  D.  T.  knife  switch  marked  "Sw"  is  closed  on  side  marked 
''buzzer."  An  A.  C.  current  of  high  E.  M.  F.  is  induced  in  the 
secondary  winding  of  the  induction  coil  by  interrupted  current  in 
the  primary  and  its  path  is  as  follows :  G,  earth  or  one  side  of 
line  (if  metallic  circuit  is  used)  ;  "receiving  circuit,  telegraph"  of 


LARGE  CON  DENSE.*     __ 
SMALL  CONDCNSER<«jRV 


BOTTOM  VIEW  OF  BACKBOARD  SHOWING  WIRING 


FIG.    30.-SERVICE    BUZZER    CIRCUITS 

distant  buzzer,  other  side  of  line,  L,  contact  1  of  key   (key  is  de- 
pressed), B,  A,  other  side  of  secondary  winding  of  induction  coil. 

Receiving  Circuit — Telegraph 

S.  P.  D.  T.  knife  switch  marked  "Sic"  is  closed  on  side  marked 
"buzzer."  A.  C.  current  of  high  E.  M.  F.  reaches  L   from  distant 


296  MILITARY  SIGNAL  CORPS  MANUAL 

instrument  by  one  side  of  line,  contact  3  of  key  (key  raised),  re- 
ceiver, C,  switch  marked  "Sw,"  G,  other  side  of  line  to  distant  in- 
strument. 

Primary    Sending    Circuit — Telephone 

S.  P.  D.  T.  knife  switch  marked  "Sw"  is  closed  on  side  marked 
"talk";  from  positive  end  of  battery  through  primary  winding  of 
induction  coil,  to  A,  to  B,  through  blade  of  switch  marked  "Sw" 
to  C,  through  push-button  switch  marked  "PB,"  through  transmitter 
to  negative  side  of  one  unit  of  the  tungsten  type  A  battery  . 

Secondary  Sending  Circuit — Telephone 

S.  P.  D.  T.  knife  switch  marked  "Six/'  is  closed  on  side  marked 
"talk."  When  sound  waves  fall  upon  the  diaphragm  of  the  trans- 
mitter, an  alternating  current  of  high  E.  M.  F.  is  induced  in  sec- 
ondary winding  of  the  induction  coil.  Starting  with  secondary  of 
induction  coil,  to  G,  to  earth  or  one  side  of  line  (if  metallic  cir- 
cuit be  used),  through  "receiving-circuit-telephone"  of  distant  in- 
strument, returning  on  other  side  of  line,  to  L,  through  contact  3 
of  key  marked  "K"  (key  raised),  to  receiver,  to  C,  to  switch 
marked  "Sw,"  through  blade  of  this  switch  to  B,  to  A,  to  other  side 
of  secondary  winding  of  induction  coil. 


FIG.    31.-SERVICE    BUZZER 
Receiving   Circuit — Telephone 

S.  P.  D.  T.  knife  switch  marked  "Sw"  is  closed  on  side  marked 
'"talk."  An  alternating  current  of  high  E.  M.  F.  induced  in  the 
secondary  winding  of  induction  coil  in  distant  instrument  reaches 
the  buzzer  over  outside  line,  to  L,  thence  to  contact  3  of  key  marked 
"K,"  to  receiver,  to  C,  to  switch  marked  "Sw."  through  blade  of 
this  switch  to  B,  to  A,  through  secondary  winding  of  induction  coil 
to  G,  to  earth  or  line  (if  metallic  circuit  be  used),  to  distant  buz- 
zer. 


THE  SERVICE  BUZZER 


297 


When  an  existing  telegraph  line  is  utilized,  the  switch  marked 
"con  ffuf'  should  be  thrown  to  the  "O"  position  in  order  that  the 
condenser  "Con"  will  be  placed  in  the  circuit. 

The  service  buzzer  is  shown  in  accompanying  Figures  31  and 
32,  it  being  shown  dismantled  in  figure  32  to  facilitate  preparation 
of  requisitions  for  renewal  parts. 

The  instrument  is  contained  in  an  aluminum  case  fitted  with  a 
hinged  cover,  both  of  which  are  covered  externally  with  a  russet- 
colored,  smooth-finish  leather  which  is  neatly  sewed  and  riveted  in 
place.  The  overall  outside  dimensions  of  the  case  are  approx- 
imately 3^4  by  5%  by  7l/2  inches.  The  two  units  of  tungsten  type 


FIG.  32.-SERVICE  BUZZER,  DISMANTLED 

Key  to  reference  numbers:—!,  case;  2,  main  cord  with  terminals;  3,  ground 
rod,  type  D;  4,  plug;  5,  connector,  type  A;  6,  transmitter;  7,  receiver; 
8,  head  band;  9,  base;  10,  induction  coil;  11,  condensers;  12,  condenser 
connecting  blocks;  13,  short-circuit  switch;  14,  holding  clip;  IS,  jack 
I>lug;  16,  transfer  switch;  17,  vibrator;  18,  sending  key;  19,  binding  post; 
20,  large  screw  driver;  21,  small  screw  driver;  22,  handle  for  screw 

-     drivers   and   wrench;   23,    tungsten    battery,    type   A. 


298  MILITARY  SIGNAL  CORPS  MANUAL 

A  battery  are  contained  in  a  chamber  located  in  the  bottom  and 
are  accessible  without  opening  the  main  cover,  there  being  an  addi- 
tional small  hinged  cover  in  one  end  of  case  which  is  fastened  se- 
curely, when  closed,  by  a  substantial  spring  clip,  and  by  a  flap  of 
leather. 

The  instrument  may  be  operated  with  both  covers  closed,  which 
is  highly  advantageous  in  inclement  weather.  To  accomplish  this 
there  is  a  suitable  opening  for  leading  out  the  cords  to  the  receiver 
and  transmitter,  and  in  main  cover,  directly  over  the  sending  key, 
is  a  round  aperture  which  is  made  moisture-proof  by  means  of  a 
covering  of  extremely  flexible  pigskin.  The  sending  key  can  be 
readily  operated  through  this  flexible  pigskin. 

The  sending  key,  induction  coil,  condensers,  plug  jack,  transfer 
switch,  vibrator,  and  binding  posts  for  transmitter  and  receiver 
cords  are  mounted  upon  a  common  base  of  hard  rubber.  Wiring 
to  the  component  parts  is  routed  in  the  under  side  of  this  base, 
which  is  mounted  in  the  front  of  the  case  above  the  battery  cham- 
ber previously  mentioned.  In  the  rear  of  the  instrument  is  a  com- 
partment of  leather  for  containing  the  transmitter,  receiver,  and 
cord  for  connecting  them.  At  one  end  of  this  chamber,  neatly 
mounted  on  a  hard  rubber  strip,  is  a  socket  wrench  for  adjusting 
the  nuts  which  secure  the  transmitter  and  receiver  terminals,  also 
two  screw  drivers — one  large  and  one  small — which  are  so  con- 
structed that  the  shanks  may  be  inserted  in  the  end  of  socket 
wrench,  thereby  using  the  socket  wrench  as  a  handle. 

Invariably  there  is  furnished  with  this  instrument  a  two-con- 
ductor cord,  approximately  5  feet  long,  one  end  of  which  is 
equipped  with  a  substantial  plug  similar  to  those  used  in  connection 
with  telephone  switchboards.  At  other  end  one  of  the  conductors 
is  equipped  with  a  Williams  test  clamp  for  connection  to  line,  the 
other  conductor  being  equipped  with  a  Signal  Corps  type  D  ground 
rod.  The  Williams  test  clamp  is  so  constructed  that  to  attach  it 
to  the  line,  it  is  merely  necessary  to  compress  the  two  principal 
parts,  releasing  them  when  the  line  has  been  inserted  in  space  pro- 
vided. One  side  of  this  clamp  is  equipped  with  an  11-point  stud 
securely  threaded  to  test  clamp.  These  points  make  excellent  con- 
tact on  line,  regardless  of  whether  the  line  be  insulated  or  not. 
By  this  means  a  quick  connection  can  be  made  to  buzzer  wire  or 
field  wire  which  is  insulated,  and  when  the  clamp  is  removed  the 
abrasion  to  insulation  is  negligible.  There  is  an  opening  in  the  case 
of  the  buzzer  through  which  the  plug  is  inserted  when  connection 
is  desired,  and  when  plug  is  so  inserted  it  makes  a  positive  con- 
nection by  means  of  a  substantial  jack  mounted  on  the  base  as  pre- 
viously indicated. 

The  case  has  an  adjustable  carrying  strap,  one  end  of  which  is 
equipped  with  a  snap  connection,  the  other  end  being  sewed  to 


Till! 


i  BUZZER 


299 


hinged  fitting  on  case.  The  instrument,  including  carrying  strap, 
type  D  ground  rod,  Williams  test  clamp,  plug  and  5-foot  cord, 
weighs  approximately  5  pounds,  and  full  directions  for  operation, 
together  with  a  circuit  diagram,  are  attached  to  the  inside  of  the 
main  cover. 

Figure  33  shows  the  circuits  employed  in  sending  and  receiving 
Morse  signals  by  means  of  service  buzzers.  It  will  be  noted  that  a 
single  conductor  is  used  to  connect  the  two  instruments,  and  that 
the  earth  is  used  for  other  conductor  of  the  circuit.  This  is  the 
customary  manner  of  connecting  two  or  more  service  buzzers  in 
the  field. 


SENDI NG  STATION  ^^ 


RECDV1NG  STATION 


FIG.  33.— CIRCUITS  EMPLOYED  IN  SENDING  AND  RECEIVING  MORSE 
SIGNALS    WITH   SERVICE    BUZZER 


INDUCTION  TELEGRAPH  SET 

The  induction  telegraph  set  (figure  1)  is  strictly  a  portable  field 
instrument  which  was  developed  by  the  Signal  Corps.  It  is  de- 
signed for  sending  Morse  signals  over  field  lines  of  communication 
and  other  lines  where  it  is  difficult  to  supply  the  large  amount  of 
battery  required  for  ordinary  telegraphic  work.  It  can  also  be 
used  for  the  transmission  of  speech  by  making  certain  modifica- 
tions. The  instrument  comprises  a  wooden  case,  the  dimensions 
of  which  are  W/2  by  7)4  by  6  inches,  outside.  The  top  of  the  case 
contains  instructions  for  operating  and  a  diagram  of  circuits.  A 
baseboard,  which  is  removable  by  means  of  four  screws,  has  on  its 
underside  the  wiring  and  on  its  upper  surface  a  battery  case  of 
aluminum  to  hold  two  tungsten  batteries;  an  induction  coil  of  the 
closed  magnetic  circuit  type;  a  double  contact  telegraph  key  of 
standard  pattern ;  a  polarized  sounder,  which  will  be  described 
later;  a  double-pole  double-throw  switch  for  reversing  the  con- 
nections to  1  e,  and  three  binding  posts  numbered  1,  2,  and  3. 
In  addition,  authority  has  been  issued  by  the  Chief  Signal  Officer  to 
install  a  fourth  binding  post  on  all  instruments  in  service,  to  be 
connected  to  the  contact  of  the  bottom  battery.  This  is  for  the 
purpose  of  attaching  external  battery  to  this  instrument  and  for 
this  purpose  the  batteries  in  the  case  must  be  removed  and  external 
battery  connected  to  binding  posts  3  and  4.  The  line  is  connected 
to  binding  posts  1  and  2  as  usual.  This  set  can  be  used  for 
ordinary  Morse  telegraphy,  in  which  case  the  line  is  connected  to 
binding  posts  2  and  3,  and  the  small  blocking  screw  which  pre- 
vents the  switch  of  the  key  from  being  closed  should  be  run  down 
with  a  screw  driver  so  that  the  switch  may  be  kept  normally  closed 
when  not  sending. 

Previous  models  of  the  field  induction  telegraph  set  used  a 
polarized  relay  of  a  well-known  commercial  form,  and,  in  addition, 
required  a  local  battery  and  local  sounder  to  be  connected  to  the 
relay  tongue.  The  model  1912  set  contains  what  is  known  as  a 
"polarized  sounder."  It  consists  of  a  regular  local  sounder  frame, 
underneath  which  is  mounted  a  strong  permanent  magnet,  the 
cores  of  the  coil  forming  the  pole  pieces  of  the  magnet.  The  coils 

300 


IXIH'CTIOX    Tl-Ll'GRAl'll   SET 


301 


are  so  wound  that  a  current  in  one  direction  tends  to  increase 
the  strength  of  the  magnet  and  in  the  other  direction  tends  to  de- 
crease the  strength  of  the  magnet.  The  armature  is  adjusted  by 
means  of  a  spring,  so  that  it  remains  in  either  the  up  or  down 
position  when  no  current  is  flowing.  When  an  instantaneous  cur- 
rent comes  over  the  line  due  to  the  depression  of  the  key  at  the 
distant  station,  the  direction  of  winding  is  such  that  the  magnetism 
is  suddenly  increased  and  the  armature  is  drawn  to  the  down 
position.  It  remains  there  after  the  instantaneous  current  has 


Fig.  1.— Induction  telegraph  set.  Key  to  reference  numbers:  1,  2,  3.,  binding 
posts;  4,  case;  5,  cover;  6,  hinge;  7,  circuit  diagram  frame;  8,  circuit 
diagram;  9,  cover  fastener;  10,  battery  case;  11,  tungsten,  type  A,  battery; 
12,  D.P.D.T.  switch;  13,  switch  handle;  14,  key;  15,  spring  for  key;  16, 
spring  adjusting  screw  for  key;  17,  rear  adjusting  screw  for  key;  18,  key- 
trunnion  screw  and  lock  nut;  19,  key  handle;  20,  sounder;  21,  sounder  base 
trunnion  screw  and  lock  nut;  19,  key  handle;  20,  sounder;  21,  sounder  base; 
22.  sounder  armature;  23,  sounder  armature  supports;  24,  sounder  perma- 
nent magnet;  2S,  coils  for  sounder;  26,  armature  movement  adjusting 

screw;  27,   spring  tension   adjusting  screw;  28,  induction   coil. 


302 


MILITARY  SIGXAL   CORPS  MAXL'AL 


ceased.  When  the  key  at  the  distant  station  is  opened  and  an  in- 
stantaneous current  in  the  opposite  direction  flows  through  the 
instrument,  the  magnetism  of  the  cores  is  suddenly  decreased  with 
the  result  that  the  armature  lies  to  the  up  position  and  there 
remains.  If  the  line  is  not  too  long  nor  too  high  a  resistance, 
and  particularly  if  there  are  not  too  many  instruments  in  series 
on  the  line,  the  sound  made  by  this  instrument  imitates  very  closely 
that  made  by  a  local  sounder.  It  may  be  that  the  pulses  from  the 
distant  station  will  come  in  reversed,  and  for  this  purpose  the 
double-pole  double-throw  switch  is  provided  which  reverses  the 
connection  of  the  sounder  to  the  line.  If  the  signals  come  in  re- 
versed, it  is  only  necessary  to  turn  the  switch  over  when  they 
will  come  in,  in  the  proper  direction. 

THEORY 

Figure  2  shows  the  theory  of  operation  of  the  field  induction  set. 
Circuit  A  comprises  a  key,  primary  of  an  induction  coil,  and 
battery.  Circuit  B  comprises  the  secondary  of  the  induction  coil 


COIL 


i                                         ^ 

o 

*     8 

0 

0 

6 

o 

0 

0 

o 

s 

BATTERY 

LINE 


FIG.  2.— THEORY  OF  OPERATION,  INDUCTION  TELEGRAPH  SET 

and  a  polarized  sounder  or  relay.  When  the  key  is  closed  in  circuit  A 
there  is  an  instantaneous  electromotive  force  induced  in  the 
secondary  of  the  induction  coil  which  causes  an  instantaneous 
current  to  flow  through  the  polarized  instrument  and  to  bring 
its  armature  to  a  certain  position  in  which  it  will  remain  after  the 
instantaneous  current  has  ceased.  When  the  key  in  circuit  A 
is  opened  there  will  be  a  similar  instantaneous  electromotive  force 
tending  to  make  a  current  flow  in  the  opposite  direction  in 
circuit  B.  This  current  will  bring  the  armature  of  the  polarized 
instrument  to  its  other  position,  in  which  it  will  remain  after  the 
current  has  ceased.  As  this  secondary  electromotive  force  may  be 
very  high,  and  as  polarized  instruments  can  be  made  to  operate  on 
extremely  small  currents,  this  induction  telegraph  arrangement 
will  operate  over  lines  of  high  resistance,  although  the  battery  in 
the  primary  circuit  may  be  one  of  only  a  few  volts. 


INDUCTION    TELEGRAPH   SET 


INSTRUCTIONS  FOR  OPERATING 


303 


To  install  batteries  —  Open  door  of  the  battery  case  by  releasing 
spring,  at  the  same  time  placing  the  forefinger  against  the  inside 
of  the  door  through  the  small  aperture  in  metal  case.  Insert 
top  battery  unit,  negative  or  flat  end,  first  and  lower  unit,  positive 
or  bottom  end,  first. 

To  use  as  an  Induction  telegraph  set  —  Connect  line  to  binding 
posts  1  and  2.  Lock  circuit  closing  lever  in  the  open  position  by 
unscrewing  small  setscrew  in  key  base  until  it  projects  sufficiently 
to  lock  the  lever.  If  the  sounder  fails  to  respond,  change  the 
direction  of  the  current  through  the  sounder  by  throwing  the 
reversing  switch. 


FIG.  3.— CIRCUITS  OF  INDUCTION  TELEGRAPH  SET 

To  use  as  a  closed-circuit  telegraph  set — Remove  batteries  from 
case.  Connect  line  to  posts  Nos.  2  and  3 ;  release  circuit-closing 
lever  by  screwing  locking  screw  down  until  it  is  flush  with  the 
base. 

Circuits — As  an  induction  telegraph ;  when  the  key  is  depressed 
current  from  -f-  of  battery  flows  through  primary  of  coil,  key,  front 
contact  to  --  of  battery.  The  instantaneous  secondary  current 
flows  from  secondary  of  coil,  through  switch,  polarized  sounder 
(operating  it),  to  binding  post  2,  line,  distant  station,  ground, 
binding  post  1,  secondary.  The  instantaneous  secondary  current 
on  opening  the  key  follows  the  same  path  in  the  opposite  direction. 
Incoming  impulses  through  line  to  binding  post  2  go  through  the 
switch,  polarized  sounder,  key,  back  contact  of  key,  binding  post  1, 
ground.  The  purpose  of  the  back  contact  of  the  key  is  to  short- 
circuit  the  secondary  of  the  induction  coil  and  so  remove  its  im- 


304  MILITARY  SIGNAL   CORPS   MAXTAL 

pedance   from  the  circuit  when  receiving.     It  is  not  essential  and 
the  key  may  be  replaced  by  one  having  no  back  contact. 

As  a  closed-circuit  telegraph ;  external  battery  one  jiole  to 
ground,  the  other  to  binding  post  3.  Batteries  in  instrument  re- 
moved. Circuit,  binding  post  3,  front  contact  of  key,  key,  reversing 
switch,  sounder,  binding  post  2,  line.  Note  that  circuit  closing 
lever  on  key  must  be  closed  when  not  sending. 

The  resistance  of  the  primary  of  the  induction  coil  installed  at 
present  in  these  instruments  is  very  low,  and  the  batteries  run 
down  very  quickly  in  service.  All  officers  in  charge  of  installa- 
tions using  these  instruments  should  keep  this  in  mind  and  keep 
constant  requisitions  for  new  batteries  going  forward.  Wherever 
possible,  as  in  permanent  or  semi-permanent  stations,  external 
battery  should  be  installed.  The  type  of  external  battery  is  im- 
material, about  6  to  10  volts  being  a  good  E.M.F.  to  use. 

DUPLEX  OPERATION 

The  field  induction  telegraph  set  may  easily  be  duplexed,  follow- 
ing the  simple  principles  of  the  differential  polar  duplex  system.  The 
only  additional  equipment  required  is  an  artificial  line  which  can 
be  adjusted  to  have  the  same  resistance  and,  with  long  lines,  the 
same  capacity  as  the  line  itself.  For  duplex  operation  the  line  must 
be  connected  to  binding  post  No.  2.  The  green  wire  normally 
connected  to  outside  binding  post  U  on  the  polarized  sounder  must 
be  shifted  to  inside  binding  post  U,  and  the  connecting  bar  join- 
ing inside  U  to  inside  D  must  be  in  place.  The  artificial  line  goes 
between  outside  U  and  binding  post  No.  1,  and  the  ground  is 
attached  to  binding  post  No.  1. 

Artificial  line  for  duplex — Any  resistance  box,  sliding  rheostat, 
or  other  variable  resistance  whose  maximum  value  is  equal  to  or 
greater  than  the  resistance  of  the  Tine  and  distant  instrument. 
If  the  line  has  appreciable  capacity,  as  in  the  case  of  a  long  line  or 
one  in  cable  or  laid  on  the  ground,  a  balancing  capacity  can  be 
constructed  of  the  2  m.f.  condensers  used  in  common  battery  tele- 
phones. They  are  cheap  and  easily  obtained.  Fractions  of  2  m.f. 
can  be  obtained  by  putting  condensers  in  series.  Close  static  balance 
is  rarely  necessary. 

Installation — In  large  offices  the  operators  should  have  in  front 
of  them  only  the  local  sounder  and  key.  All  other  apparatus 
should  be  in  a  separate  room  under  charge  of  an  expert.  This 
plan  is  especially  necessary  where  duplex  and  repeater  sets  are  in- 
stalled. In  small  offices  the  circuits  should  be  well  installed  without 
unnecessary  complication,  and  full  instructions  for  operating  and 
adjusting  should  be  furnished.  Operators  put  in  charge  of  such 
stations  should  receive  special  instruction  before  assuming  charge, 
as  the  induction  telegraph  system  is  not  used  commercially  at 
present,  in  spite  of  its  many  advantages. 


RADIOTELEGRAPHY 

ELECTRIC  CHARGES  AND  STATIC  FIELDS  OF  FORCE 

Electrical  phenomena  may  be  grouped  in  two  general 
classes.  One  of  static  electricity,  when  the  electrical  charges 
are  at  rest,  and  the  other  of  dynamic  or  current  electricity, 
when  the  charges  are  in  motion  along  a  conductor. 

When  an  insulator,  such  as  sealing  wax,  is  rubbed  with  fur, 
or  a  glass  tube  with  silk,  it  acquires  the  property  of  attracting 
light  bodies  near  it,  and  is  said  to  be  charged.  This  action 
shows  that  forces  exist  in  the  adjacent  space,  and  there  is  said 
to  be  an  electrostatic,  or,  more  briefly,  a  static  field  of  force 
about  the  charged  body.  When  two  bodies  are  brought  near 
together  they  may  be  either  attracted  or  repelled,  depending 
on  the  nature  of  the  two  charges.  If  the  rubbed  glass  is 
brought  near  particles  touched  and  charged  by  the  rubbed 


FIG.   l.-A  FIELD  OF  FORCE   BETWEEN   CHARGED  BODIES 
305 


306  MILITARY  SIGNAL  CORPS  MANUAL 

sealing  wax  they  will  be  attracted  to  it,  and  similarly  if  the 
rubbed  sealing  wax  is  brought  near  particles  charged  by  the 
rubbed  glass  they  will  be  attracted ;  but  two  bodies,  both  of 
which  have  been  charged  by  either  the  glass  or  the  wax,  will 
repel  each  other.  Hence  like  charges  repel  each  other  and 
unlike  charges  attract.  The  names  positive  (glass)  and  nega- 
tive  (sealing  wax)  have  been  given,  respectively,  to  these 
charges.  By  means  of  a  delicately  suspended  insulated  body 
the  static  forces  can  be  mapped  out  along  directions  in  general 
perpendicular  to  the  charged  surfaces.  In  figure  1  is  shown  in 
section  the  static  field  of  force  between  a  positively  charged  and  a 
negatively  charged  body  in  which  the  direction  of  the  field  at  any 
point  is  indicated  by  the  direction  of  the  arrows  at  that  point, 
and  the  intensity  or  strength  of  the  field  in  any  area  is  indicated  by 


FIG.  2.— STATIC  LINES  BETWEEN  TWO  POSITIVELY  CHARGED  BODIES 


the  number  of  lines  in  that  area.  It  is  seen  that  most  of  the 
lines  are  crowded  together  between  the  two  as  though  there 
was  an  actual  pull  along  their  length,  thus  suggesting  attrac- 
tion. Similarly  in  figure  2  are  shown  the  static  lines  between 
two  bodies  with  positive  charges  which  are  apparently  driven 


RADIOTELEGRAPHY 


307 


apart,  thus  suggesting  repulsion. 
If  both  charges  were  nega- 
tive the  direction  of  the  ar- 
rows would  be  reversed,  but  the 
static  lines  would  have  the 
same  shape  as  before.  In  figure 
3  are  shown  in  elevation  the 
static  lines  from  a  positively 
charged  wire  near  the  surface 
of  the  earth.  If  the  wire  were 
negatively  charged,  the  signs  of 
the  charges  and  the  direction 

FIG.  3.-STATIC  LINES  FROM  A    of    the     arrows    would    be     re- 
POSITIVELY  CHARGED  WIRE        versed. 

CURRENTS  AND  MAGNETIC  FIELDS  OK  FORCE 

If  a  wire  connects  a  charged  body  with  an  uncharged  or 
oppositely  charged  one,  the  static  charge  will  flow  through 
the  wire  from  the  charged  to  the  uncharged  body,  or  from  the 
positively  charged  body  to  the  negatively  charged  one,  and 
become  a  current  while  so  flowing,  that  is,  a  current  is  a 
moving  charge  or  succession  of  charges.  If  the  same  charge 
is  continuously  renewed  there  is  a  steady  or  direct  current, 


FIG.   4.— MAGNETIC    FIELD   OF    PERPENDICULAR    WIRE 

often  abbreviated  as  D.C.  If  the  charges  are  continuously 
varying  in  intensity  and  sign  and  the  variations  are  periodic 
in  character,  there  is  an  alternating  current  or  A.C. 

While  the  current  is  flowing  in  the  wire  it  has  been  found 
that  there  exists  around  it  a  field  of  force  of  another  kind.  If 
a  horizontal  magnetic  needle  is  brought  near  a  vertical  wire  in 
which  a  direct  current  is  flowing,  the  needle  will  be  deflected  and  the 
direction  in  which  it  will  point  depends  upon  the  direction  iu 


308  Ml  LIT  A  KY  SIGNAL  CORPS  MANUAL 


FIG.  5.— MAGNETIC  FIELD  OF  HORIZONTAL  WIRE 

which  the  current  is  flowing.  This  action  shows  that  mag- 
netic forces  exist  in  the  adjacent  space,  and  the  wire  carrying 
the  current  is  said  to  have  a  magnetic  field  about  it.  The  lines 
of  magnetic  force  may  be  mapped  out  with  iron  filings  or  a 


FIG.  6.— STATIC  FIELD  OF  POSITIVELY  CHARGED  WIRE 

magnetic  compass.  Thus,  if  the  compass  is  moved  in  the  direc- 
tion indicated  by  the  deflection  of  its  needle  it  will  trace  out 
circles  around  the  wire  at  a  center  and  in  planes  perpendicular 
to  it. 


RADIOTELEGRAPHY 


309 


In  figure  4  is  shown  a  section  of  wire,  perpendicular  to  the 
paper  and  carrying  a  current  downward  through  it,  surrounded 
by  circles,  which  by  the  direction  of  the  arrows  indicate  the 
direction  of  the  magnetic  field  at  any  point,  and  by  the  number 
of  lines  in  any  area  indicate  the  intensity  of  the  magnetic  field 
in  that  area.  If  the  direction  of  the  current  in  the  wire  were 
reversed  so  as  to  flow  up  through  the  paper,  the  direction  of 
the  arrows  would  have  to  be  reversed.  Similarly,  in  figure  5 
the  wire  is  shown  lyjng  on  the  paper  and  the  current  flowing 
toward  the  top  of  the  page,  with  the  magnetic  lines  (appearing 
as  dots)  going  down  through  the  paper  on  the  right  of  the 
wire  and  coming  up  through  on  the  left. 


STATIC  AND  MAGNETIC  FIELDS  NEAR  A  WIRE 

If  a  long  wire  is  placed  vertically,  and  positive  and  negative 
charges  are  alternately  applied  at  the  bottom  and  flow  along 
the  wire,  there  will  be  near  the  wire  alternately  opposite  static 
fields,  due  to  the  charges;  and  at  the  same  time  alternately 
opposite  magnetic  fields,  due  to  the  alternating  currents. 
Figure  6  shows  in  perspective  the  wire  with  a  positive  charge, 


FIG.   7.— STATIC    FIELD   OF   NEGATIVELY   CHARGED   WIRE 


310 


MILITARY  SIGNAL   CORPS  MANUAL 


surrounded  by  its  vertical  static  field  S  and  its  horizontal  field 
M,  and  figure  7  the  wire  with  a  negative  charge  and  both  its 
fields  reversed  in  direction.  Figure  8  shows  both  the  static 
and  magnetic  lines  as  seen  when  projected  on  the  plane  below 
the  wire  where  the  magnetic  lines  are  circles,  as  in  figure  4, 
and  the  static  lines  are  straight,  being  radial  with  respect  to 
the  circles. 


RADIATION  OF  ELECTROMAGNETIC  WAVES 

These    two    fields    of    force    changing    their    direction    and 
intensity  with  great  rapidity  and  traveling  outward  from  the 


FIG.    8.— STATIC    AND    MAGNETIC    LINES    ON   THE    PLANE 
BELOW  THE  WIRE 

wire  in  the  medium  called  the  cihfr  with  the  velocity  of  light, 
300,000,000  meters  or  186,000  miles  per  second,  are  the  electro- 
magnetic waves  of  radio-telegraphy.  They  spread  simultane- 


RADIOTELEGRAPHY 


511 


ously  radially  outward  and  upward  from  the  vertical  wire  or 
antenna  as  it  is  called.  The  energy  of  the  varying  electric 
charges  and  currents  is  thus  imparted  to  the  medium,  or  is 
radiated. 

The  two  fields  constituting  the  wave  and  their  outward 
motion  in  radiation  are  shown  in  a  general  way  in  figure  9, 
where  the  electric  field  is  indicated  as  lines  and  the  magnetic 
field  is  perpendicular  to  the  plane  of  the  paper.  At  great  dis- 
tances from  the  transmitting  antenna  the  static  lines  become 
straight  and  perpendicular  to  the  surface  of  the  earth  and  the 
magnetic  lines  straight  and  parallel  to  the  surface. 

These  static  and  magnetic  lines  of  force,  moving  with  the 
velocity  of  light,  sweep  across  the  antenna  at  the  receiving 


1* Wa*f  knqfh 

FIG.   9.-THEORY   OF   THE   ELECTRO-MAGNETIC   WAVE   TRAIN 

station.  The  vertical  static  lines  in  the  wave  are  directed 
alternately  upward  and  downward  and  produce  in  the  antenna 
moving  charges  of  alternately  opposite  signs ;  that  is,  an  alter- 
nating current.  At  the  same  time  the  horizontal  magnetic 
lines  are  directed  alternately  to  the  right  and  left,  and  when 
cutting  across  the  antenna  produce  an  alternating  current  in 
it.  The  resultant  current  generated  by  these  two  fields  gives 
an  alternating  current  in  the  receiving  antenna  quite  similar 
to  that  in  the  transmitting  antenna,  although  of  course  much 
weaker.  It  is  these  alternating  currents  which  produce  the 
signals  in  the  receiving  apparatus. 

MEASUREMENT  OF   POTENTIAL  BY   SPARK   DISCHARGE 

If  large  charges  of  opposite  signs  are  given  to  two  insulated 
bodies  close  together,  a  spark  will  jump  between  them  and  the 


312  MILITARY  SIGNAL  CORPS  MANUAL 

potential  is  said  to  be  high.  The  distance  between  the  points 
of  two  needles  mounted  in  the  same  line  may  be  used  to 
measure  this  potential.  The  distance  between  two  brass  balls 
each  2  centimeters  (about  25/32  inch)  in  diameter  also  may  be 
used.  It  will  be  found  that  the  needle  points  are  more  useful 
at  low  voltages,  as  from  5,000  to  15,000,  and  the  brass  balls 


SPARKING  DISTANCE  BETWEEN  NEEDLE  POINTS 


FIG.    10.-VOLTAGE    CURVE    FOR    MEASURING    POTENTIAL 
BETWEEN  NEEDLES 


more  useful  at  the  higher  values.  In  figures  10  and  11  are 
given  the  voltage  curves  for  the  needle  and  the  ball  gaps. 
Thus,  if  the  discharge  occurs  between  needle  points  one-half 
of  an  inch  apart  the  potential  is  15,000  volts.  In  Tables  1  and 
2  are  given  the  values  from  which  the  curves  are  plotted  in 
which  the  potential  is  the  maximum  or  peak  value,  and  not  the 
value  which  would  be  indicated  on  a  high  voltage  voltmeter. 


RADIOTELEGRAPH )  313 

TABLE  I.— NEEDLE  POINTS 

(Adapted  from  the  table  of  the  American  Institute  of  Electrical 

Engineers) 

Sparking  Maximum 

Distance  potential 

in  inches  in  volts 

0.15 5,000 

.20 6,400 

.30 9,300 

,40 12,200 

.50 - . .  15,000 

.60 17,700 

.70 20,500 

.80 23.100 

0.90 25,700 

LOO 28,300 

.10 30,700 

.20 33,000 

.30 35,300 

.40 37,500 

.50 39700 

.60 41,909 

.70 43.9CO 

.80 45,800 

1.90 47,600 

2.00 49,500 

The  potential  is  the  maximum  or  peak  value. 

TABLE  II.— BRASS  BALLS  2  CENTIMETERS  IN  DIAMETER 

(Adapted     from    Prof.     Fleming's     book,     "The     Princip!es     of 
Electric  Wave  Telegraphy.") 

Sparking  Maximum 

Distance  potential 

in  inches  in  volts 

0.05 : 5,700 

.10 10,000 

.20 17,700 

.30 25,000 

.40 31;,700 

.50 36,700 

.60 40,600 

.70 44,300 

.80 47,700 

.90 50,800 

1.00..      53,400 


314  MILITARY  SIGNAL   CORPS  MANUAL 


FIG.    11.— VOLTAGE   CURVE   FOR   POTENTIAL   BETWEEN   BALL   GAPS 

SYSTEMS  OF  UNITS 

Inductances  and  capacities  are  essential  elements  in  the  cir- 
cuits for  generating  and  detecting  electromagnetic  waves. 
Their  definitions  and  the  units  in  which  they  are  measured  will 
be  briefly  given  in  the  following  paragraphs: 

A  condenser  is  said  to  have  capacity,  which  may  be  defined 
as  its  property  of  storing  the  energy  of  electric  charges  in  the 
form  of  an  electrostatic  field. 

A  coil  is  said  to  have  inductance,  which  may  be  defined  as 
its  property  of  storing  the  energy  of  electric  currents  in  the 
form  of  a  magnetic  field. 

Capacity  and  inductance,  as  well  as  the  other  electrical 
quantities,  can  be  measured  in  three  different  systems  of  units, 
the  electrostatic,  electromagnetic,  and  practical.  From  some 
points  of  view  it  is  unfortunate  that  three  different  systems 
have  come  into  use,  but  it  is  now  impossible  to  abandon  any 


RAD1OTELEGRAPHY  315 

one  of  them.  The  relations  between  the  systems  may  be 
briefly  explained  as  follows: 

The  units  of  the  electrostatic  system  may  be  considered  as 
based  on  the  value  of  a  unit  quantity  or  charge  of  electricity 
such  that  if  two  bodies  are  charged  with  it  they  will  repel  each 
other  with  a  unit  force  when  placed  at  a  unit  distance  apart. 
If  this  charge  flows  along  a  wire  it  becomes  a  current,  and  if 
the  unit  charges  are  renewed  at  the  rate  of  one  every  second 
the  current  so  obtained  is  called  a  unit  current  in  the  electro- 
static system.  The  units  of  the  electromagnetic  system  may  be 
considered  as  based  on  the  value  of  a  unit  current  of  electricity 
such  that  its  magnetic  field  will  exert  the  same  unit  force  as 
mentioned  on  a  body  with  a  unit  magnetic  field  when  placed 
at  a  unit  distance  from  a  unit  length  of  wire  carrying  this 
current.  The  current  so  defined  is  called  the  unit  current  in  the 
electromagnetic  system. 

The  strength  or  intensity  of  these  two  unit  currents  is  not 
the  same;  in  fact,  it  is  very  different,  that  of  the  current  in  the 
electromagnetic  system  being  30,000,000,000  times  stronger  than 
the  unit  current  in  the  electrostatic  system.  The  units  of  the 
other  electrical  quantities,  as  capacity,  inductance,  resistance, 
etc.,  are  likewise  nearly  all  different  in  the  two  systems,  in 
some  cases  the  units  being  larger  in  one  system  than  in  the 
other,  and  vice  versa.  Owing  to  the  inconvenient  size  of  the 
units  in  the  two  previous  systems,  suitable  fractions  or  multi- 
ples of  these  units  have  been  chosen  as  the  units  of  the 
practical  system.  The  numerical  relations  between  the  units 
of  the  three  systems  are  given  in  textbooks,  so  that  only  a  few 
of  the  more  useful  ones  will  be  included  in  the  table  which 
follows.  . 

It  is  sometimes  convenient  to  abbreviate  the  words  "electro- 
static" and  "electromagnetic"  to  "static"  and  "magnetic,"  as 
has  been  done  in  the  table,  and  also  to  write  more  shortly  E.S. 
and  E.M. 

When  capacity  is  measured  in  the  practical  system  the  units 
are  the  farad  and  the  one-millionth  part  of  a  farad,  called  the 
microfarad,  and  in  the  electrostatic  system  the  unit  is  the 
centimeter.  The  relation  between  the  two  as  shown  in  the 
table  is  as  follows : 

Number  of  static  units  of  centimeters      __   nurnber     of     practical 

900,000  ~ 
units  or  microfarads ;  thus, 

1 000  1 

909 


316 


MILITARY  SIGNAL   CORPS  MANUAL 


Similarly  900,000  X  number  of  microfarads  =  number  of  cen- 
timeters. 

The  unit  of  capacity  in  the  electromagnetic  system  has 
received  no  name,  but  if  a  capacity  is  measured  in  the  units 
of  this  system,  they  can  be  converted  into  those  of  the  other 
systems  by  means  of  the  table. 

When  inductance  is  measured  in  the  practical  system  the 
unit  is  the  henry  with  its  fractional  parts,  as  the  one-thou- 
sandth part,  called  the  millihenry,  and  the  one-millionth  part. 
called  the  microhenry.  Thus,  i/ 1,000  henry  —  i  millihenry,  and 
1/1,000,000  henry  =  1  microhenry;  1  henry  =  1,000  millihenrys  = 
1,000,000  microhenrys.  In  the  electromagnetic  system  the  unit 
of  inductance  is  the  centimeter.  It  is  to  be  noted  that  the 
name  of  this  unit  is  the  same  as  that  of  the  unit  of  capacity 
in  the  electrostatic  system,  an  unfortunate  choice  which  can 
not  now  be  changed.  The  relation  between  the  units  of  induc- 
tance of  the  two  systems  is  as  follows  : 

Number  of  magnetic  units  or  centimeters ^pr    of  tical 

1,000.000,000 

units,  or  henrys ;  and  similarly  1,000,000,000  X  number  of  Henrys 
=  number  of  centimeters;  1,000  cms.  =  1  microhenry^ 
1/1,000,000  henry  =  .000,001  henry;  1,000,000  cms.  =  I  millihenry 
=  1/1,000  henry  =  .001  henry;  1,000,000,000  cms.  =  1  henry.  Thus 


1 


henry  == 


henry  =  0.002  henry. 


500  1,000 

=  .002X1,000,000   microhenrys  =  2,000   microhenrys. 

=  .002  X  1,000  millihenrys  =2  millihenrys. 

=  .002X1,000,000,000  cms.  =  2,000,000  cms. 

The  unit  of  inductance  in  the  electrostatic  system  has 
received  no  name  but  can  be  converted  into  units  of  the  other 
systems  by  the  table. 

Table  for  changing   some   of   the   more   common   units  from    one 
system   to  another. 

CAPACITY. 


Electrostatic  units 
(in    cms.). 

Electromagnetic  units 
(no  name). 

Practical  units 
(in  mfd.). 

To  magnetic. 

To  practical. 

To  static. 

To  practical. 

To  static. 

To  magnetic. 

Divide  by 
9X1020 

Divide  by 
900,000 

Multiply  by 
9x10=° 

Multiply  by 
.IxlO15 

Multiply  by 
900,000 

Divide  by 
IxlO15 

{Table  continued  on  next  page) 


RADIOTELEGRAPHY 


317 


(Table  continued  from  preceding  page) 
INDUCTANCE. 


Electrostatic  units             Electromagnetic  units 
(no  name).                                 (in   cms.). 

Practical  units 
(in  henrys). 

To  magnetic. 

To  practical. 

To  static. 

To  practical. 

To  .static. 

To  magnetic. 

Multiply  by 
9x10™ 

Multiply  by 

9xl011 

Divide  by 

9X1020 

Divide  by 
1x10" 

Divide  by 
9xl011 

Multiply  by 
1x10° 

CURRENT. 


Electrostatic  units 
(no  name). 

Electromagnetic  units                 Practical  units 
(no  name).                               (in   amperes). 

To  magnetic. 

To  practical. 

To  static. 

To  practical. 

To  static. 

To.  magnetic. 

Divide  by 
3X101  ° 

Divide  by 
3x10" 

Multiply  by 
3xl010 

Multiply  by 
10 

Multiply  by 
3x10° 

Divide  by 

10 

POTENTIAL. 


Electrostatic  units 
(no  name). 

Electromagnetic  units 
(no  name). 

Practical  units 
(in  volts). 

To  magnetic. 

To  practical. 

To  static. 

To  practical. 

To  static. 

To  magnetic. 

Multiply  by 
3xl010 

Multiply  by 
300 

Divide  by 
3x10'  ° 

Divide  by 
IxlO8 

Divide  by 
300 

Multiply  by 
1x10" 

RESISTANCE. 


Electrostatic  units 
(no  name). 

Electromagnetic  units    i             Practical  units 
(no  name).                                (in  ohms). 

To  magnetic. 

To  practical. 

1 
To  static. 

To  practical. 

To  static. 

To  magnetic. 

Multiply  by 
9X1020 

Multiply  by 
9xlOl  ' 

Divide  by 
9x.IV 

Divide  by 
IxlO9 

Divide  by 
9X1011 

Multiply  by 
1x10" 

It  will  be  noted  that  in  many  cases  the  units  have  received 
no  name  in  some  of  the  systems  in  which  they  are  expressed, 
so  that  the  name  of  the  system  must  be  given;  thus  a  current 
of  1  ampere  is  a  current  of  3,000,000,000  units  of  current  in  the 
electrostatic  system,  or  3,000,000,000  electrostatic  units  of 
current. 


318  MILITARY  SIGNAL   CORPS  MANUAL 

Owing  to  the  large  numbers  which  must  be  used  in  con- 
verting units  from  one  system  to  another  it  is  usual  to  abbrevi- 
ate as  in  algebrr;  thus,  3,000,000,000  is  written  3  X  10",  where  the 
number  9  indicates  the  number  of  times  that  the  cipher  or  zero 
must  be  written  after  the  number  3,  and  similarly  900,000,000,- 
000,000,000,000  is  written  9  X  1020. 

The  table  may  be  used  to  convert  from  one  system  to 
another,  as  follows :  A  potential  of  2.S  units  in  the  E.S.  system 
is  equal  to  2.5  X  300  units  in  the  practical  system,  or  750  volts  ; 
current  of  1.0  ampere  in  the  practical  system  is  equal  to 
1.0 -=-10  units  of  current  in  the  E.M.  system,  or  0.1  unit  in  the 
E.  M.  system;  an  inductance  of  1/500  henry  is  equal  to  1/500X 
109  E.M.  units  of  inductance  or  centimeters,  or  1  500X1, 000,- 
000,000  =  2,000,000  cms. 

MECHANICAL  AND  ELECTRICAL  OSCILLATIONS 

The  following  illustrations  and  explanations  of  oscillatory 
discharges  and  their  occurrence  in  resonant  circuits  are  intro- 
duced here  so  as  to  give  a  clear  understanding  of  these  most 
important  principles. 

OSCILLATORY    DISCHARGES 

If  a  strip  of  steel  is  clamped  at  one  end  and  the  free  end  is 
pulled  to  one  side  and  released,  this  end  will  not  only  return 
to  its  normal  position  but  will  swing  past  it,  and  returning  it 
will  swing  past  in  the  opposite  direction,  but  not  so  far  as 
before  and  will  thus  execute  a  series  of  oscillations,  each  of 
which  takes  place  in  the  same  length  of  time  expressed  in 
fractions  of  a  second,  which  will  gradually  die  down  to  zero, 
or  are  said  to  be  damped.  The  free  end  returns  to  its  normal 
position  because  of  the  elasticity  of  the  metal,  and  swings 
beyond  it  because  of  its  inertia.  The  energy  stored  up  in  the 
spring  in  pulling  it  to  one  side  is  thus  gradually  wasted  in 
friction,  etc.  In  a  similar  way  in  electrical  circuits  we  have 
to  deal  with  capacity,  which  corresponds  to  the  elasticity,  and 
inductance,  which  corresponds  to  the  inertia. 

If  a  condenser  of  consider- 
able capacity  C,  such  as  a  number 
of  Leyden  jars  or  condenser 
plates  in  parallel,  is  connected  in 
a  circuit  with  a  coil  L  and  spark 
gap  S,  as  shown  in  figure  12, 
and  the  potential  on  the  con- 
denser gradually  increased, 
^uite  a  large  charge  may  be  FIG.  12— CIRCUIT  FOR  DAMPED 
Stored  in  it  before  the  potential  OSCILLATIONS 


RAD10TELEGRAPI1Y 


319 


rises  high  enough  to  cause  a  spark  at  the  gap.  When,  how- 
ever, the  gap  breaks  down,  the  charge  in  the  condenser  dis- 
charges through  the  gap  and  the  coil,  and  on  account  of  the 
inductance  (inertia)  in  the  circuit  it  overshoots  in  the  same 


/&        _.S^-3-- 

Time^jn^Mri/ionths  of  a  second 


FIG.  13.— HIGHLY  DAMPED  WAVE  TRAIN 

way  as  the  spring,  then  discharges  in  the  opposite  direction, 
etc.,  so  that  the  charge  may  oscillate  many  times  back  and 
forth  across  the  gap  before  it  is  so  used  up  In  heat  that  not 
enough  charge  remains  to  jump  across  again.  The  charged 
condenser,  as  C  of  figures  12  and  16,  is  thus  the  immediate 
source  of  the  energy  of  the  electrical  oscillations.  Its  rapid 
oscillatory  discharge  through  the  gap  S  and  the  inductance  L 
takes  place  in  the  form  of  a  series  of  decreasing  oscillations, 
called  a  train  of  damped  oscillations  or  a  damped  wave  train. 


FIG.   14.— SLIGHTLY  DAMPED  TRAIN  OF  OSCILLATIONS 

In  some  circuits  there  may  be  twenty,  thirty,  or  even  more 
such  oscillations  in  a  wave  train.  Figure  13  represents  dis- 
charges in  which  the  oscillations  die  down  quickly,  and  are 
said  to  be  strongly  damped  or  highly  damped.  Figure  14  repre- 


320  MILITARY  SIGNAL  CORPS  MANUAL 

sents  discharges  in  which  the  oscillations  die  down  gradually 
and  are  said  to  be  feebly  damped  or  slightly  damped.  Figure 
15  represents  discharges  in  which  the  oscillations  do  not  lie 


FIG.    15.-WAVE   TRAIN   OF  UNDAMPED   OSCILLATIONS 

down  and  are  said  to  be  undamped  oscillations,  continuous 
oscillations,  or  sustained  oscillations.  These  undamped  oscilla- 
tions can  not  be  generated  by  the  discharge  of  a  condenser 
through  an  ordinary  spark  gap,  but  may  be  developed  by  means 
of  a  special  type  of  direct-current  arc  with  metal  or  metal  and 
carbon  electrodes,  or  by  special  high-frequency  alternators. 
Both  the  arc  and  alternator  methods  of  the  generation  of 
undamped  oscillations  are  now  in  use. 


FREQUENCY 

The  rate  of  vibration  of  the  steel  spring  or  number  of  vibra- 
tions per  second  depends  upon  the  weight,  distribution,  and 
elasticity  of  the  metal.  Similarly  in  the  electrical  circuit,  when 
the  condenser  discharges  across  the  gap  and  through  the  induc- 
tance, the  rate  of  the  electrical  oscillations,  or  frequency  in 
number  of  oscillations  per  second,  depends  upon  the  capacity 
of  the  condenser  and  the  inductance  of  the  coil.  The  larger 
the  product  of  the  capacity  and  inductance,  the  slower  is  the 
rate  of  the  oscillations  ;  that  is,  the  fewer  the  number  of  oscil- 
lations per  second  and  the  lower  the  frequency,  and  vice  versa, 
the  smaller  the  product  of  the  capacity  and  inductance  the 
more  rapid  is  the  rate  of  the  oscillations  per  second  and  the 
higher  the  frequency.  The  formula  for  the  number  of  oscilla- 

tions per  second  is   n  =  -  =.  where  L  is   the   inductance  in 


circuit  and  henrys  and  C  the  capacity  in  farads;  thus,  if  C  is 
0.000,000,004    farad    (0.004    microfarad)    and    L    is    0.001    henry 


RADIO  TELEGRAPHY  321 

(1,000,000  cms.  or  1  millihenry),  then  the  oscillations  are  taking 
place  at  the  rate  of  about  79,600  per  second.       . 

_  1  1 


_  _ 
6.28V0.001  X  0.000,000,004  ~  6.28  V  0^00000,000,004 

RESONANCE 

The  principles  of  resonance  can  be  illustrated  by  the  steel 
spring,  preferably  in  the  form  of  two  tuning  forks.  If  a  loud 
note  from  one  tuning  fork  is  sounded  near  another  fork,  the 
latter  will  be  set  in  vibration  slightly,  even  if  the  pitch  of  the 
note  or  number  of  vibrations  per  second  is  not  the  same  as 
that  which  the  latter  itself  would  give.  If,  however,  the  note 
is  of  the  same  pitch,  then  each  successive  vibration  of  the 
prongs  will  be  re-enforced  by  air  waves  of  the  same  frequency 
as  its  own,  and  stronger  vibrations  will  be  produced  by  this 
note  than  by  any  other.  Under  these  conditions  the  two  forks 
are  said  to  be  in  resonance.  Similarly  if  a  circuit  containing 
a  coil  1,  condenser  c,  and  very  small  spark  gap  s,  all  in  series, 
is  brought  near  another  circuit  LCS,  as  shown  in  figure  16,  in 


8 

FIG.    16.-CIRCUITS   IN    RESONANCE 

which  oscillations  are  taking  place,  then  small  sparks  may  DC 
seen  passing  across  the  gaps  of  the  first  circuit,  showing  tkat 
currents  are  being  induced  in  it.  If,  however,  adjustments  are 
made  in  the  number  of  the  Leyden  tubes  in  circuit  or  in  the 
number  of  turns  of  inductance  by  means  of  the  sliding  contact, 
then  generally  the  size  and  brightness  of  the  sparks  will  be 
increased  up  to  a  certain  point,  and  any  further  changes  in 
either  the  inductance  or  the  capacity  will  make  the  sparks 
smaller  and  fainter.  At  the  adjustment  which  gives  the  largest 
and  brightest  sparks  the  induced  oscillations  are  the  strongest 
and  of  the  same  frequency  in  the  two  circuits;  that  is,  the  two 
circuits  are  sytonised,  or  tuned,  or  are  in  resonance. 


322 


MILITARY  SIGNAL   CORPS  MAXUAL 


POWER    CIRCUITS 


TRANSFORMERS 

After  each  oscillatory  discharge  the  charge  in  the  condenser 
is  renewed  at  regular  intervals  by  an  induction  coil,  or  alter- 
nating current  transformer.  The  former  is  but  little  used  now, 
and  will  not  be  described  here.  The  transformer  is  an  appara- 
tus for  increasing  the  comparatively  low  voltage  of  an  alter- 
nating current  dynamo  or  generator  to  the  high  voltage 
necessary  to  cause  the  condenser  charge  to  jump  across  the 
spark  gap.  The  details  of  transformer  construction  are 
described  in  textbooks  on  electricity.  It  will  suffice  to  say  here 
that  it  consists  of  a  primary  winding  of  a  comparatively  few 
turns  of  heavy  wire,  wound  on  but  insulated  from  a  laminated 
iron  or  iron-wire  core,  which  carries  the  current  fom  the 
alternator ;  a  secondary  winding  of  many  turns  of  finer  wire 
wound  in  sections  and  well  insulated  from  all  other  parts  of 
the  transformer,  which  delivers  a  smaller  current,  but  at  the 
necessarily  higher  voltage,  to  the  condenser  that  is  charged 
thereby.  In  general  the  transformer  increases  the  alternator 
of  primary  voltage  in  the  same  proportion  as  the  number  of  sec- 
ondary turns  is  increased  over  the  number  of  the  primary  turns. 
The  voltage  of  the  alternator  impressed  on  the  primary  of  the 
transformer  is  usually  110  or  220  volts;  the  voltage  of  the 
Secondary  which  is  impressed  on  the  condenser  depends  upon 
the  size  of  the  radio  set  and  varies  between,  say,  10,000  and 
30,000  volts. 

In  the  case  of  quenched  spark  sets  a  transformer  is  generally 
used  in  which  by  a  proper  choice  of  the  capacity  connected  to 
its  secondary  circuit,  the  secondary  voltage  is  increased  by 


•« Primary 

FIG.    17.— FIELD  OF   TRANSFORMER   OPEN   MAGNETIC   CIRCUIT 


RADIOTELEGRAPH  Y 


323 


resonance  to  perhaps  twice  as  many  times  as  the  ratio  of  the 
primary  and  secondary  turns  would  indicate.  Such  a  trans- 
former is  called  a  resonance  transformer. 

Transformers  may  be  divided  into  two  classes,  depending  on 
the  type  of  the  laminated  core,  whether  with  the  open  mag- 
netic circuit,  as  shown  in  figure  17,  or  with  the  closed  magnetic 
circuit,  as  shown  in  figure  18.  These  terms  apply  to  the  iron  as 
a  path  for  the  magnetic  field.  Thus  in  figure  18  it  is  seen  that 
the  magnetic  lines  M  have  a  continuous  path  or  circuit  through 
the  iron,  or,  as  it  is  said,  a  closed  magnetic  circuit,  whereas  in 
figure  17  the  path  of  the  lines  is  partly  through  the 
space  outside,  or,  as  it  is  said,  an  open  magnetic  circuit.  In 
both  figures  the  direction  of  the  field  as  it  exists  at  one  instant 
is  indicated  by  arrows,  but  it  must  be  remembered  that  the 
field  is  continually  reversing  its  direction  as  the  alternating 
current  changes  its  direction.  Both  types  of  transformers  are 
in  general  use,  although  it  is  probable  that  the  closed  magnetic 
type  is  now  being  used  more  than  the  other.  There  is  no  es- 


FIG.    18.-CLOSED    MAGNETIC    CIRCUIT 

sential  difference  in  efficiency  of  operation.  Practical  experience 
has  shown,  however,  that  in  general  it  is  not  always  possible 
to  interchange  transformers  of  the  two  types  in  any  one  set, 
particularly  in  quenched  spark  sets,  where  the  alternator, 
transformer,  and  condenser  of  the  closed  oscillating  circuit 
must  be  designed  as  a  whole  to  secure  the  best  results. 

Transformers  may  be  divided  into  two  types,  depending  on 
the  nature  of  the  insulation,  whether  oil  insulated  or  dry 
insulated.  In  the  first  the  transformer  is  completely  immersed 
in  a  suitable  insulating  oil,  such  as  transil  oil,  in  an  iron  tank 
provided  with  a  cover  to  keep  the  oil  from  spilling,  through 
which  the  terminals  extend,  strongly  insulated,  as  with  porce- 
lain for  example.  In  the  second  type  strong  insulating  fabrics 
or  materials  arc  used  around  and  between  the  windings  which 


324 


MILITARY  SIGNAL   CORPS  MANUAL 


are  saturated  with  a  nonfluid  insulating  compound.  In  the 
higher  voltage  transformers  of  both  types,  the  secondary  coils 
are  often  heated  in  a  vacuum  to  remove  the  air  and  moisture, 
dipped  in  an  insulating  varnish  or  compound,  and  baked  until 
they  are  hard  so  as  to  protect  the  windings,  exclude  moisture, 
etc. 

The    connections    of    the    transformer,    etc.,    are    shown    in 
figure  19  where  A  is  the  alternating  current  generator,  K  the 


+  G 


Jk 

t 


FIG.   19.— THE  TRANSFORMER   CONNECTED   IN   CIRCUIT 

telegraph  key,  T  the  transformer  with  primary  and  secondary 
windings,  C  the  condenser,  S  the  spark  gap,  and  L  the  induc- 
tance. There  is  no  essential  difference  in  operation  of  the  two 
kinds  of  connections,  the  choice  generally  being  made  on 
account  of  some  convenience  of  wiring. 


ALTERNATORS 

The  transformer  receives  its  power  from  an  alternating 
current  generator,  or  alternator,  as  it  is  often  called,  which  is 
either  belt  or  chain  driven  from  an  engine  or  electric  motor, 
or  directly  driven  by  electric  motor,  in  which  case  the  two 
machines  are  mounted  on  the  same  bedplate  and  the  shafts 
connected  by  a  flexible  coupling,  the  set  being  called  a  motor- 
generator  set.  The  two  essential  parts  of  an  alternator  from 
an  electrical  point  of  view  are  the  fields  and  the  armature.  A 


RADlOTELEGRAPJty  325 

direct  current  is  supplied  to  the  former  and  an  alternating 
current  is  delivered  by  the  latter.  Alternators  are  built  in  three 
general  types,  with  revolving  field,  revolving  armature,  and  of 
the  inductor  types,  the  last  two  being  generally  used  in  radio 
work.  In  the  revolving  armature  type  the  fields  are  stationary 
and  the  armature  rotates,  its  wires  thus  cutting  the  magnetic 
lines  from  the  field  windings  and  generating  the  alternating 
current  which  is  brought  out  by  brushes  bearing  on  two 
collector  rings,  or  slip  rings,  as  they  are  called.  In  the  inductor 
type  both  the  field  and  the  armature  are  stationary,  the 
rotating  part  being  simply  an  iron  form  with  projecting  pole 
pieces,  the  rotation  of  which  carries  the  magnetic  lines  from 
the  fields  in  and  out  of  the  fixed  armature,  the  wires  of  which 
thus  cut  the  magnetic  lines  and  generate  the  alternating  cur- 
rent. In  this  type  of  machine  there  are  no  revolving  wires  or 
moving  contacts  of  any  kind.  The  moving  part,  as  armature, 
field,  or  inductor,  as  the  case  may  be,  is  called  the  rotor.  The 
stationary  part  is  called  the  stator. 

The  alternator  fields  require  a  direct  current  for  their  ener- 
gizing, which  may  be  furnished  either  by  an  outside  direct- 
current  source,  such  as  the  direct-current  mains  that  supply  the 
power  to  run  the  direct-current  motor  of  a  motor-generator 
set,  or  by  an  exciter,  which  is  a  small  direct-current  machine 
that  may  be  mounted  on  the  alternator  shaft  or  may  be  a 
separate  machine  independently  driven  by  any  convenient 


RHEOSTAT   AND   REACTANCE   CONTROL 

In  order  to  control  the  power  delivered  to  the  transformer 
a  variable  resistance  or  rheostat  is  sometimes  inserted  in  series  in 
the  circuit  of  the  alternator  armature  and  transformer  primary ; 
in  other  cases  a  variable  inductance  called  a  reactance  or  reac- 
tance regulator  is  used,  consisting  of  coils  of  heavy  wire,  with 
taps  brought  out  at  different  points,  wound  on  a  laminated  iron 
core.  The  rheostat  and  the  reactance  may  serve  a  similar  but 
not  necessarily  the  same  purpose;  thus  increasing  the  resist- 
ance in  the  rheostat  always  decreases  the  power  delivered  to 
the  transformer,  and  increasing  the  reactance  may  do  likewise. 
In  these  cases  the  rheostat  or  reactance  may  normally  be  cut 
out  of  circuit  and  introduced  only  as  needed  to  cut  down  the 
power,  as  for  example,  when  it  is  desired  to  decrease  the  range 
of  a  set  so  as  not  to  cause  interference  at  a  distant  station  or 
when,  as  required  by  law,  a  ship  station  reduces  its  power  as 
it  comes  within  fifteen  miles  of  a  naval  or  military  station. 

Increasing  the  reactance  does  not  always  cut  down  the 
power;  in  fact,  in  some  circuits  of  the  quenched-spark  type  it 


326  MILITARY  SIGNAL   CORPS  MANUAL 

may  actually  increase  the  power  delivered  to  the  transformer, 
and  hence  to  the  antenna,  where  it  causes  an  increase  in  the 
antenna  current.  The  reason  for  this  is  that  there  is  a  com- 
bined adjustment  of  the  inductances  in  the  transformer  primary 
and  secondary  circuits  and.  of  the  capacity  of  the  closed  circuit 
condenser  which  is  best  adapted  for  the  charging  of  this  con- 
denser at  regular  intervals.  In  some  cases  more  inductance 
is  required  than  that  in  the  alternator  armature,  and  the  trans- 
former primary,  and  it  is  then  added  as  a  reactance  in  the 
primary  circuit.  In  other  cases  the  inductance  may  be  added 
as  a  reactance  in  the  secondary  circuit,  where  evidently  the  coil 
must  be  designed  to  withstand  high  potentials.  In  a  few  cases 
reactances  are  added  in  both  circuits  so  as  to  secure  the 
desired  results.  When  the  best  adjustments  have  been  attained 
it  is  often  found  that  the  transformer  primary  current  drops 
to  a  minimum  value,  the  antenna  current  rises  to  a  maximum, 
and  at  the  same  time  the  note  of  the  spark  is  the  clearest. 


KEYS 

In  the  smaller  sizes  of  radio  sets  the  current  from  the 
alternator  to  the  transformer  can  be  controlled  by  ordinary  types  of 
Morse  keys,  with  either  silver  or  platinum  contacts,  without 
troublesome  sticking,  trailing,  or  arcing  even  at  fast  sending. 
In  the  larger  sizes,  however,  special  means  of  cutting  down 
the  arc  at  the  breaking  of  the  circuit  must  be  used,  such  as 
shunting  the  key  by  a  resistance,  condenser,  reactance,  etc.,  so 
that  the  key  does  not  break  the  whole  current.  In  the  largest 
sets  a  relay  key  is  generally  furnished,  which  consists  of  an 
electromagnet,  the  windings  of  which  are  in  series  with  an 
ordinary  Morse  key  and  a  source  of  direct  current,  and  the 
armature  of  which  carries  the  heavy  contacts  necessary  to  break 
the  current  in  use.  Such  a  key  may  be  used  to  break  a  current 
of  50  or  60  amperes  or  more  without  injurious  sparking.  In 
some  cases  a  single  large  key  with  contacts  an  inch  or  so  in 
diameter  and  a  handle  a  foot  long  has  been  used. 

Another  type  of  key  is  coming  into  use,  known  as  a  "break 
key,"  which  permits  the  receiving  operator  to  break  the  trans- 
mitting operator  as  on  a  wire  line.  Among  other  ways  this 
may  be  accomplished  by  providing  the  ordinary  key  with  an 
extra  set  of  contacts  which,  just  after  the  current  has  been 
broken  in  making  a  dot  or  dash,  and  just  as  the  key  handle 
comes  up  to  its  final  position,  automatically  connects  the 
receiving  circuit  to  the  antenna  and  ground  without  the  neces- 
sity of  throwing  a  special  switch.  At  any  time  that  the 
receiving  operator  misses  a  word  or  desires  to  "break"  the  transmit- 


RADIOTELEGRAPHY 


327 


ting  operator  he  ftolds  his  key  down  or  calls  "bk,"  and  the  trans- 
mitting operator  with  the  telephones  on  his  head  and  with 
his  detector  in  adjustment  will  hear  the  call  between  the  dots 
and  dashes  of  his  own  sending  and  thus  be  broken.  For  most 
successful  use  both  operators  should  be  provided  with  break 
keys.  It  is  essential  that  the  receiving  circuits  in  general  and 
the  detector  in  particular  be  protected  from  sparks  from  the 
transmitting  circuits,  and  that  the  operators  be  not  bothered 
by  the  sounds  from  their  spark  gaps  or  machinery. 

DEFINITIONS   OF   ALTERNATING-CURRENT   TERMS 

For  a  proper  understanding  of  some  of  the  points  on  the 
following  pages,  definitions  and  explanations  will  be  given  of 
the  more  common  terms  in  use  in  the  employment  of  alternating 
currents. 

The  frequency  with  which  the  charges  in  the  condenser  C 
of  figure  19  are  renewed  by  the  transformer  depends,  among 
other  things,  upon  the  rate  at  which  the  voltage  and  current 


FIG.  20.— SINE  CURVE  OF  CURRENT  FROM   ALTERNATOR 


delivered  by  the  alternator  is  varying.  Figure  20  represents 
the  manner  in  which  these  quantities  vary,  where  the  set  of 
values  ABCDE,  half  of  which  is  positive  and  half  negative,  is 
called  a  cycle  of  voltage  or  current,  the  symbol  for  which  is 
often  thus  v/ritten  '-.  The  number  of  cycles  per  second  Is 
called  the  frequency  and  the  letter  "n"  or  "f"  is  often  used  as 
its  symbol.  In  commercial  alternators  used  in  radio  telegraphy 
the  frequencies  are  generally  60,  120,  480,  or  500  cycles  per 
second;  that  is,  there  are  60,  120,  etc.,  complete  sets  of  values, 
such  as  ABCDE  of  figure  20  per  second,  or  n  =  60,  120,  etc. 
Half  a  cycle,  such  as  the  set  of  values  ABC  or  CDE  of  figure 
20,  which  may  be  either  positive  or  negative,  is  called  an  alter- 
nation. There  are  always  twice  as  many  alternations  per 


328  MILITARY  SIGNAL  CORPS  MANUAL 

second  as  there  are  cycles.  The  frequency  of  an  alternating 
current  is  sometimes  given  in  alternations  per  minute  instead 
of  cycles  per  second,  thus  a  current  of  60  cycles  per  second  is 
of  the  same  frequency  as  one  of  7,200  alternations  per  minute. 
The  time  taken  to  complete  one  cycle  is  called  the  period,  and 
the  letter  T  is  often  used  as  its  symbol,  thus  if  there  are  500 
cycles  per  second,  the  time  to  complete  one  cycle  is  1/500 

second    or   0.002    second;    that    is,    T  =  ^p  second,    or   T  =  0.002 

second.  Similarly  the  time  for  one  alternation  of  a  current  of 
the  same  frequency  is  1/1,000  second  or  0.001  second.  The  rela- 
tion between  the  frequency  in  cycles  per  second  and  the  period 

in  fractions  of  a  second  is  given  by  the  formula  T=    -r-r-    or 


The  highest  value  of  the  current  or  voltage  in  any  alterna- 
tion, as  at  points  B,  D,  etc.,  of  figure  20  or  the  corresponding 
points  in  figures  13,  14,  and  15,  is  called  the  amplitude,  or  some- 
times the  peak  of  the  curve. 

It  will  be  noted  that  there  is  a  similarity  between  the  sus- 
tained oscillations  as  represented  in  figure  15  and  the  alter- 
nating current  or  voltage  as  represented  in  figure  20.  The 
two  curves  have  the  same  shape  or  form,  being  known  in  trigo- 
nometry as  sine  curves,  but  they  differ  in  the  greatly  increased 
frequency  of  a  hundred  thousand  or  million  per  second  in  the 
radio  circuits  (the  closed  and  open  oscillating  circuits),  as  com- 
pared with  that  of  60  to  500  per  second  in  the  power  circuits 
(the  alternator  and  transformer  circuits).  It  is  the  general 
practice  to  speak  of  the  number  of  oscillations  or  of  cycles  per 
second  in  radio  circuits,  but  only  of  the  number  of  cycles  per 
second  in  power  circuits. 

If  the  voltage  or  current  varies  as  a  sine  curve,  as  in  figures 
15  and  20,  the  voltmeter  or  ammeter  will  not  read  the  peak  or 
amplitude  value,  because  this  value  lasts  for  only  a  short  part 

of  the  total  time,  but  a  fractional  part,  0.707= =  of   the 

//> 

V 

peak  value.     Similarly  if  the  voltmeter  or  ammeter  reading  is  given, 
the    peak    value    or    amplitude    can    be    found    by    multiplying    by 
I 

1.41  =  T~ 


KADIOTELEGRAPHY  329 

The  frequency  of  the  alternating  current  is  sometimes  indicated 
by  a  frequency  meter,  which  in  one  type  consists  of  a  series  of  flat 
steel  springs  or  reeds,  each  with  a  different  period  of  mechanical 
vibration  which  is  marked  on  it,  the  whole  series  covering  a  range 
of  frequency  of  from,  say,  470  to  530  vibrations  per  second.  Behind 
the  springs  is  an  electromagnet  carrying  the  alternating  current, 
the  frequency  of  which  is  to  be  measured.  When  the  frequency  of 
the  electromagnetic  impulses  is  the  same  as  that  of  any  one  of  the 
reeds  it  is  set  into  vibration  by  resonance  with  these  impulses,  and 
the  frequency  of  the  current  is  then  the  same  as  that  marked  on  the 
reed  in  vibration. 


HIGH-FREQUENCY  CIRCUITS 
CLOSED  OSCILLATING  OR  PRIMARY  CIRCUIT 

The  circuit  of  coil  L,  condenser  C,  and  spark  gap  S,  as  shown 
in  heavy  lines  in  figure  19,  is  called  the  closed  oscillating  or  primary 
circuit,  as  distinguished  from  the  open,  radiating  or  secondary  cir- 
cuit to  be  described  later.  These  three  elements  are  always  con- 
nected in  series  to  form  the  circuit,  which  is  found  in  all  spark 
excitation  types  of  radio  stations.  There  are  two  different  methods 
of  connecting  the  transformer  secondary  leads  to  this  circuit  for 
the  charging  of  the  condenser,  one  of  which  is  shown  in  the  upper 
part  of  figure  19,  where  the  condenser  is  seen  to  be  directly  across 
the  transformer  secondary  leads,  and  the  other  in  the  lower  part 
where  the  spark  gap  is  so  connected.  In  this  latter  case  the  con- 
denser is  charged  through  the  inductance  L,  but  its  resistance  and 
inductance  are  so  small  as  compared  with  that  of  the  transformer 
secondary  as  to  have  no  effect  in  the  charging.  There  is  no  essen- 
tial difference  in  the  operation  of  the  two  types  of  connections. 

The  actions  taking  place  in  the  closed  circuit  as  a  whole  are  as 
follows :  The  condenser  begins  to  get  its  charge  at  the  beginning 
of  each  alternation,  as  at  points  A,  C,  E,  etc.,  of  figure  20,  and 
reaches  such  a  potential  as  to  cause  its  discharge  across  the  gap  and 
through  the  inductance  at  the  peaks  of  the  curve,  as  at  points  B,  D, 
etc.  The  condenser  is,  so  to  speak,  a  reservoir  which  is  filled  and 
discharged  1,000  times  per  second  in  a  500-cycle  alternator  set. 
In  figure  21  the  upper  curve  represents  the  500-cycle  alternating 
current  delivered  by  the  transformer  secondary  to  the  condenser 
which  is  charged  thereby;  the  lower  curve  represents  the  dis- 
charge of  the  condenser,  producing  damped  wave-trains  of  per- 
haps 20  or  30  oscillations,  each  train  lasting  a  few  millionths  or 
hundred  thousandths  of  a  second,  as  shown  in  figures  13  and 
14.  In  order  to  be  able  to  show  the  wave  trains  at  all  in  figure 


330 


MILITARY  SIGNAL   CORPS  MAXUAL 


21  their  duration  must  be  shown  much  exaggerated  as  compared 
with  the  intervals  between  them.    Thus,  if  the  period  of  each 

1 
complete    oscillation    in    the    train    were     c'     second    and 


there    were    twenty-five    oscillations    in    the    train,    each    train 
25  1 


would    persist    for 


second,    or 


second,   or    the 


500,000  '    20,000 

duration    of    each    wave    train    is    only    one-twentieth    of    that 
between  successive  trains. 

It  must  be  noted  that  although  the  transformer  secondary 
is  connected  to  the  closed  oscillating  circuit,  as  shown  in  figure 


FIG.    21.— A    DAMPED    WAVE-TRAIN 


19,  it  takes  no  part  in  the  oscillations  of  this  circuit.  The 
reason  for  this  is  that  the  period  of  the  circuit  of  the  trans- 
former secondary  and  closed  circuit  capacity  is  so  long  (in 
fractions  of  a  second)  on  account  of  the  large  secondary 
inductance  that  the  wave  train  in  the  closed  oscillating  circuit 
has  been  completed  before  the  transformer  secondary  circuit 
has  had  time  to  complete  a  part  of  one  of  its  own  slow  oscilla- 
tions. The  period  or  frequency  of  the  oscillations  of  the  closed 
circuit  is  thus  independent  of  the  transformer  circuit. 

In  the  preceding  example  it  has  been  assumed  that  there 
was  one  discharge  in  each  alternation  or  two  discharges  per 
cycle;  that  is,  1,000  wave  trains  per  second.  In  some  case.v 
however,  the  circuit  may  be  arranged  so  that  there  is  a  charge 


RADIOTELEGRAPH*7  331 

and  discharge  in  every  other  alternation — that  is,  only  one 
discharge  per  cycle — which,  with  a  500-cycle  alternator,  would 
give  only  500  wave  trains  per  second.  In  both  cases,  however, 
the  wave  trains  are  thus  separated  by  equal  intervals  of  time. 
When  the  wave  trains  are  thus  separated  by  equal  intervals 
of  time  the  note  of  the  spark  is  said  to  be  pure.  In  some  cases, 
however,  it  is  possible  to  charge  the  condenser  two,  three,  or 
even  more  times  per  alternation,  and  hence  four,  six,  or  even 
more  times  per  cycle,  and  then  it  is  said  that  these  are  multiple 
discharges.  Under  these  circumstances  the  intervals  of  time 
between  the  wave  trains  will  not  in  general  be  all  equal  and 
the  note  will  not  be  pure.  The  pure  note  is  often  very  desir- 
able, although  not  always  necessary  in  practical  work. 


WAVE   TRAIN    OR    SPARK    FREQUENCY 

The  number  of  wave  trains  per  second  is  called  the  wave- 
train  frequency  or  the  spark  frequency.  If  the  alternator  fre- 
quency is  500  cycles  per  second  and  there  is  a  discharge  once 
in  every  alternation,  or  1,000  discharges  per  second,  the  spark 
frequency  is  1,000  per  second.  It  must  be  noted  that  in  general 
the  alternator  frequency  and  the  wave-train  frequency  are  not 
the  same ;  in  fact,  they  may  be  very  different,  as  in  the  case  of 
multiple  discharges  mentioned  in  the  preceding  paragraph. 

If  the  spark  frequency  is,  say,  120  per  second,  as  from  a 
oo-cycle  alternator,  it  is  said  to  be  low,  but  if  it  is  1,000  per 
second,  as  from  a,  soo-cycle  alternator,  it  is  said  to  be  high. 
There  are  certain  advantages  in  a  high  spark  frequency  which 
appear  both  at  the  transmitting  and  at  the  receiving  stations. 
If  the  closed  circuit  condenser  is  charged  1,000  times  per  second 
to  a  certain  potential,  it  is  evident  that  more  energy  will  be 
required  than  if  charged  only  120  times,  the  formula  for  the 
energy  being  %  C  V"N,  where  C  is  the  capacity,  V  the  potential, 
and  N  the  number  of  times  per  second.  If  the  same  amount 
of  energy  is  available  in  the  two  cases — that  is,  if  ^CVN  is 
constant — the  smaller  the  value  of  N  the  larger  must  be  the 
value  of  V,  other  conditions  being  constant,  and,  vice  versa,  the 
larger  the  value  of  N  the  smaller  may  be  the  value  of  V.  The 
earlier  practice  was  to  make  N  small,  as  120  per  second^rom  a 
60-cycle  alternator,  and  V  large,  as  30,000  volts.  The  modern 
practice  is  to  make  N  large,  as  1,000  from  a  500-cycle  alternator, 
and  V  small,  which  in  this  example  must  be  about  10,800  volts. 
It  is  evident,  then,  that  the  transformer  secondary  and  the 
closed  oscillating  circuit  condenser  do  not  need  to  be  built  to 
withstand  the  high  voltages  formerly  used,  and  that,  therefore, 
they  may  be  lighter  and  more  compact;  also  that  the  oscillatioo 


332  MILITARY  SIGNAL  CORPS  MANUAL 

transformer  and  antenna, 'to  be  described  later,  do  not  need  the 
very  high  insulation  which  was  formerly  necessary. 

The  advantages  of  the  high  spark  frequency  at  the  receiving 
station  will  be  mentioned  later  under  that  heading.  If  suitable 
constants  are  used  in  the  formula  for  the  energy,  it  is  possible 
to  determine  the  capacity,  peak  voltage,  etc,  for  any  size  of 
set.  Let  K.  W.  be  the  number  of  kilowatts  that  the  trans- 
former secondary  must  deliver  to  the  closed  oscillating  circuit 
condenser;  M.  F.  the  capacity  of  this  condenser  in  microfarads; 
V.  the  peak  value  of  the  voltage  to  which  the  condenser  is 
charged  and  then  discharged  as  the  spark  gap  breaks  down; 
and  Cycles  the  number  of  cycles  per  second  of  the  alternator  in 
which  there  are  two  discharges  per  cycle,  then — 

(M.F.)  X  (V2)  X  (Cycles) 

Jv.  W.  — • — — 


10' 

Thus  if  M.F.  is  0.012  mf. ;  V.  18,250  volts,  peak  value;  and  the 
Cycles  500,  with  two  discharges  per  cycle,  then  K.  W.  will  be 
2.0.  As  it  is  impossible  to  build  a  transformer  with  an  efficiency 
of  100  per  cent,  it  is  evident  that  the  armature  of  the  alternator 
must  deliver  a  larger  number  of  kilowatts  to  the  primary  of  the 
transformer  than  is  given  by  the  above  formula.  The  actual 
number  will  be  found  by  dividing  the  secondary  kilowatts  by 
the  efficiency  of  the  transformer.  Thus,  if  the  efficiency  were 
93  per  cent.,  or  0.93,  then  the  alternator  armature  output  or  the 

2.0 
transformer    primary   input    would    be      QQ~    —2.15   K.  W.     By 

simple  changes  in  the  above  formula  it  is  evident  that  when 
any  three  of  the  quantities  are  known,  the  fourth  can  be 
found. 


TRANSMITTING  CONDENSERS 

A  brief  description  of  the  three  elements,  condenser,  coil, 
and  spark  gap,  will  be  given. 

The  functions  of  the  condenser  are,  by  virtue  of  its  capacity, 
to  store  the  charge  delivered  to  it  by  the  transformer  second- 
ary circuit  until  its  potential  reaches  the  desired  value  as  deter- 
mined by  the  spark  gap,  and  then  to  discharge  through  the  gap 
and  the  inductance.  An  ideal  condenser  would  be  one  that  was 
perfectly  insulating,  could  not  be  punctured,  and  showed  no 
heating  or  losses  of  any  kind  during  charging  and  oscillatory 
discharging. 

There  are  several  different  types  of  transmitting  condensers 
used  in  the  Signal  Corps  radio  stations,  varying  widely  in 


RADIOTELEGRAPHY  333 

capacity,  size,  voltage,  etc.,  from  the  small  mica  ones  of  the 
field  radio  sets  to  the  4%-foot  jars  or  compressed-air  types  in 
the  permanent  stations.  All  types  consist  essentially  of  two 
conducting  surfaces,  as  tin  or  copper  foil,  separated  by  an 
insulator  or  dielectric,  as  it  is  often  called,  which  can  withstand 
without  puncturing  the  high  voltage  required  to  break  down 
the  spark  gap.  Probably  the  most  efficient  condenser  is  the 
compressed-air  type,  which  consists  of  a  large  number  of  cir- 
cular metal  plates  mouhted  on  two  sets  of  supports  with  a 
small  air  space  between  each  plate,  the  top  plate  and  every 
alternate  plate  being  connected  together  as  one  set  and  the 
remaining  plates  as  the  other  set.  The  whole  is  contained  in 
an  air-tight  tank,  one  set  of  plates  being  connected  to  the  tank 
as  one  terminal  and  the  other  set  to  a  terminal  brought  out 
through  the  cover  in  a  porcelain  insulator  sealed  air-tight  by 
a  lead  gasket.  Air  is  then  pumped  into  the  tank  until  a  pres- 
sure of  about  240  pounds  per  square  inch  is  reached,  or  about 
16  atmospheres  of  15  pounds  per  square  inch,  as  shown  by  a 
pressure  gauge  on  top  of  the  tank.  At  this  pressure  it  has 
been  found  that  air  has  an  insulating  strength  many  times 
greater  than  at  ordinary  pressures.  Condensers  of  this  type 
will  withstand  a  maximum  or  "peak"  voltage  of  about  20,000 
volts  under  service  conditions.  The  most  serious  objection  is 
the  excessive  weight,  a  tank  of  about  0.006-microfarad  capacity 
weighing  about  300  pounds.  There  are  many  types  of  condens- 
ers using  glass  as  the  dielectric,  such  as  plates  or  jars  covered 
with  foil  or  plated  with  copper.  When  these  condensers  are 
used  at  high  potential,  such  as  25,000  volts  or  more,  there 
is  developed  at  the  sharp  edges  of  the  foil  or  plating  a  dis- 
charge (sometimes  called  brush  discharge),  which  spreads  out 
over  the  surface  of  the  glass,  is  accompanied  by  a  hissing  sound 
and  considerable  heating  of  the  glass  close  to  the  edges,  and 
in  a  dark  room  shows  a  pink  light  at  the  edges.  The  punctur- 
ing of  the  glass  and  the  breaking  down  of  the  condenser  often 
takes  place  close  to  the  edges,  due  probably  to  the  brush  dis- 
charge and  the  local  heating  of  the  glass.  These  discharges 
represent  losses  which,  in  part  at  least,  can  be  prevented  by 
covering  the  edges  of  the  foil  with  an  'insulating  coating,  such 
as  asphalturn,  and  more  completely  by  immersing  the  con- 
densers in  an  insulating  oil,  such  as  castor  oil,  etc. 

The  capacity  of  these  condensers  and  the  voltage  which  they 
can  withstand  depend  so  much  on  the  quality  of  glass,  the 
manner  in  which  it  was  annealed,  its  thickness,  etc.,  that  it  is 
impracticable  to  give  figures  except  for  condensers  that  have 
actually  been  tested.  The  capacity  of  one  glass  plate  about 
3-16  inch  thick  and  with  the  foil  15  inches  square,  is  about 


334  MILITARY  SIGNAL  CORPS  MANUAL 

0.0020  to  0.0025  microfarad.     The  capacity  of  a  jar  with  glass  % 
inch   thick,  4^   inches   in   diameter,  and   height   of   foil   of    10 
inches  is  about  0.002  M.  F.     In  the  case  of  a  good  grade  of  plate 
glass    about    ft    inch    thick,     free     from    scratches,   bubbles,    etc 
a  potential  of  20,000  volts,  peak  value,  can  be  safely  used. 

In  figure  22  is  shown  a  closed  oscillating  circuit  with  three 
condenser  jars  connected  in  parallel;  that  is,  the  three  outside 
coatings  are  connected  together  as  one  terminal  and  the  three 
inside  coatings  as  the  other,  and  with  a  potential  of  20,000 


I 
t 


FIG.  22.-CLOSED  OSCILLATING  CIRCUIT  WITH  CONDENSER 
JARS  CONNECTED  IN  PARALLEL 

volts  between  the  terminals.  When  condensers  are  thus  con- 
nected in  parallel  the  total  capacity  is  the  sum  of  all  the  capaci- 
ties ;  if  the  condensers  are  all  of  equal  capacity,  the  total  capa- 
city is  the  capacity  of  any  one  condenser  multiplied  by  the 
number.  Thus  in  figure  22  if  each  condenser  were  a  jar  of 
capacity  0.002  M.  F.,  the  total  capacity  would  be  0.006  M.  F.,  or 
three  times  0.002  M.  F. 


t 


M  5000  V.4«l  5000  V.»j 
I*— 30000  Volts-*) 


FIG.  23.— CONDENSERS  CONNECTED  IN  SERIES 

If  the  condensers  break  down  at  this  potential  or  if  higher 
potentials,  such  as  30,000  volts,  are  to  be  used,  two  banks,  each 
of  three  jars  in  parallel  should  be  connected  in  series,  as  shown 
in  figure  23.  It  is  to  be  noted  that  this  connection  requires 


RADIO  TELEGRAPH  Y 


335 


twice  as  many  jars  as  before,  but  if  the  total  potential  is  30,000 
volts,  the  potential  across  each  jar  is  now  only  15,000  volts 
instead  of  20,000  as  before.  Whenever  condensers  are  con- 
nected in  series,  the  total  capacity  is  always  reduced;  if  two 
equal  condensers  are  so  connected,  the  total  capacity  is  one- 
half  the  capacity  of  either;  if  three  equal  condensers  are  so 
connected,  the  total  capacity  is  one-third,  etc.  As  the  con- 
nections shown  in  figure  23  reduce  the  capacity  to  one-half  the 
desired  value  in  figure  22,  two  banks  each  of  six  jars  must  be 
connected  in  series-parallel,  as  shown  in  figure  24,  thus  requir- 
ing four  times  as  many  jars  as  the  first  circuit. 

Another  type  of  condenser  having  some  advantages  is  the 
Moscicki  jar,  which  consists  essentially  of  a  glass  tube  or  jar 
with  inside  and  outside  coatings,  as  in  the  other  types,  but  at 
the  edges  of  the  coatings  where  the  puncture  usually  takes 
place  the  glass  is  thickened  to  give  increased  strength,  and  at 
the  same  time  the  edges  are  covered  with  an  insulating  liquid 


I 


U|  5000  V»|*l  5000  V*l 
I*- 30  000  Volts ->| 


FIG.  24.— CONDENSER  JARS  IN  SERIES  PARALLEL 


to  stop  the  brush  discharge.  The  whole  is  contained  in  a  brass 
tube  to  which  the  outside  coating  is  connected,  the  inside  coat- 
ing being  brought  out  to  a  binding  post  through  a  sealed  porce- 
lain insulator.  The  case  and  the  binding  post  thus  become  the 
two  terminals.  These  tubes  are  made  in  two  sizes,  the  larger 
of  which  is  in  more  general  use,  has  capacity  of  about  0.005 
M.  F.,  and  is  capable  of  withstanding  20,000  volts. 

There  are  many  other  types  of  condensers  using  such  dielec- 
trics as  mica,  paper,  and  various  molded  insulating  compounds. 
In  a  few  cases  oil  is  used  as  the  dielectric,  in  which  case  metal 
plates  are  mounted  on  insulating  supports  a  short  distance 
apart  in  tanks  filled  with  a  suitable  insulating  oil,  such  as  cas- 
tor oil,  etc. 


336 


MILITARY  SIGNAL  CORPS  MANUAL 


TRANSMITTING   INDUCTANCES 

The  function  of  the  inductance  is  to  form  one  of  the   two 

elements,  the  condenser  being  the  other,  necessary  for  develop- 
ing and  maintaining  the  oscillations,  and  to  serve  as  a  means 
of  transferring  energy  from  one  circuit  to  another.  An  ideal 
coil  would  be  one  having  the  desired  inductance  but  with  a  zero 
resistance  to  the  oscillating  currents. 

The  inductance  coil  L,  which  has  been  shown  in  the  various 
figures,  may  be  any  one  of  several  different  types,  such  as  a 
helix  of  heavy  copper  wire,  thin-walled  copper  tubing,  or  flat 
strips,  or  a  flat  spiral  of  copper  ribbon,  such  as  the  linking  coil 
of  the  early  Signal  Corps  field  radio  sets,  etc.  These  are  gen- 
erally provided  with  clips  so  as  to  be  able  to  vary  continuously 
the  number  of  turns,  and  hence  the  inductance  in  circuit.  In 
any  single  coil,  the  fewer  the  number  of  the  turns  the  less 
will  be  the  inductance,  and  vice  versa,  the  larger  the  number  of 


.150 


7 


.100 


'.050 


10 


15 


Number  of  turns 

FIG.   25.— CALIBRATION    CURVE    OF    THE    INDUCTANCE    OF    A 
SQUARE    HELIX 


RADIOTELEGRAPHY 


337 


turns  the  greater  will  be  the  inductance.  In  some  cases  the  coil 
may  be  provided  with  plugs  and  sockets  to  vary  the  inductance 
by  steps  and  other  means  provided  elsewhere  in  the  circuit  to 
get  all  adjustments  between  the  steps. 

Curves  showing  how  the  inductance  of  a  coil  varies  with  the 
numbers  of  the  turns  in  circuit  is  called  a  calibration  curve  of 
the  inductance.  In  figure  25  is  shown  such  a  curve  for  a  helix, 
with  square  turns  wound  with  copper  tubing  about  one-fourth 
inch  in  diameter,  the  length  of  each  side  being  21%  inches  and 
the  spacing  of  the  turns  being  1  inch  between  centers.  In 
figure  26,  A  and  B,  are  shown  two  calibration  curves  of  a  flat 


.130 
.120 
.110 

.100 

.090 


^.070 

|.060 


^•040 


|.020 
*  .010 


A 


/B 


O      2      4-      6       8      10     12      14-     16     18    20    22    24    26    28    30 
Number  of  turns 

FIG.    26.-CALIBRATION   CURVES   OF   A    FLAT    SPIRAL 


spiral,  similar  to  the  one  used  in  the  field  radio  sets,  in  the 
first  of  which  (A)  the  turns  are  counted  from  the  outside 
inward,  and  in  the  second  (B)  they  are  counted  from  the  inside 
outward.  Thus  it  is  seen  that  in  using  different  numbers  of 
turns  in  a  flat  spiral  care  must  be  taken  to  state  how  the  turns 
are  counted.  Ths  explanation  of  the  difference  between  the 
two  curves  is  that,  other  things  being  equal,  the  greater  the 
diameter  of  the  turn  the  larger  will  be  the  inductance  and 
hence  the  inductance  will  be  the  larger  for  a  few  turns  in  that 


338 


MILITARY  SIGNAL   CORPS  MANUAL 


curve  in  which  the  turns  are  counted  from  the  outside  inward. 
There  is  another  useful  type  of  inductance  called  the  vari- 
ometer, which  consists  essentially  of  two  coils  connected  in 
series  or  parallel,  as  desired,  one  of  which  is  movable  with 
respect  to  the  other.  In  some  cases  one  coil  is  arranged  to 
slide  past  the  other  in  a  plane  parallel  to  its  windings,  as  indi- 
cated in  figure  27;  in  other  cases  one  coil  is  rotated  inside  the 
windings  of  the  other,  as  indicated  in  figure  28.  In  the  second 
type,  when  the  coils  are  in  the  same  plane  and  the  windings  are 
connected  so  that  the  current  is  circulating  through  them  in 
the  same  direction,  the  two  magnetic  fields  are  helping  each 
other  and  the  inductance  is  a  maximum;  if,  now,  one  coil 
is  rotated  through  an  angle  of  180  degrees  the  two  fields  are 
opposing  and  the  inductance  is  a  minimum;  for  intermediate 


FIG.  27.— SLIDING  COILS  OF 
THE  VARIOMETER 


FIG.  28.— ROTATING  COILS  OF 
THE  VARIOMETER 


angles  the  inductance  will  have  some  intermediate  value.  The 
variometer  thus  has  the  advantage  of  giving  a  continuous 
change  of  inductance  without  moving  clips  or  contacts,  but  has 
what  may  be  under  certain  conditions  the  disadvantages  of  not 
giving  zero  inductance  at  its  minimum  position  and  of  always 
having  the  resistance  of  all  its  wire  in  circuit.  A  variometer  is 
generally  used  in  connection  with  a  helix  or  coil,  variable  only 
by  steps,  to  give  intermediate  values  of  the  inductance  as 
mentioned  above. 

The  earlier  types  of  closed  circuit  inductance  were  wotind 
with  wire  or  tubing,  the  resistance  of  which  to  direct  current 
was  very  low.  Both  theory  and  experiment  have  shown,  how- 
ever, that  the  resistance  to  high-frequency  currents  may  be 
comparatively  large.  The  explanation  is  that  these  high- 
frequency  currents  tend  to  travel  almost  wholly  on  the  surface 
of  the  conductor  and  do  not  penetrate  to  any  considerable  dis- 


RADIOTELEGRAPHY 


339 


tance  into  the  wire.  Thus  a  thin-walled  tube  will  have  practi- 
cally the  same  resistance  to  high-frequency  currents  as  a  solid 
wire  of  the  same  diameter,  the  inside  of  the  wire  carrying  no 
current  at  all. 

This  tendency  of  the  current  to  flow  only  on  the  outer  sur- 
face is  sometimes  called  the  "skin  effect"  and  the  distance  to 
which  the  current  penetrates  the  thickness  of  the  skin.  The 
higher  the  frequency  the  more  marked  is  the  skin  effect  and 


Number  of  Times  of  increase  in  Resistance 


3  I  Z  3  A-  56  7  8  9  H 

frequency  Jn  Hundred  thousand  cycles 

\ 

\ 

™ 

\ 

\ 

\ 

\ 

\ 

\ 

\ 

\ 

} 

\ 

p> 


FIG.  29.— RESISTANCE  CURVE  OF  NO.  O,   B.   &  S.  COPPER  WIRE 

the  thinner  is  the  skin ;  in  other  words,  the  higher  the  fre- 
quency the  larger  will  be  the  resistance  for  the  same  size  and 
length  of  wire.  In  figure  29  is  given  the  curve  showing  the 
increase  in  resistance  for  No.  0  copper  wire,  B.  &  S.  gauge 
(about  325  mils  in  diameter),  as  the  frequency  changes  from 


340 


MILITARY  SIGNAL  CORPS  MANUAL 


zero  or  a  steady  current  up  to  1,000,000  cycles  per  second.  Thus 
at  500,000  cycles  it  is  seen  that  the  resistance  has  been  increased 
about  22  times  the  D.  C.  value.  The  scale  of  such  a  curve  will 
differ  with  the  different  sizes  of  wire,  the  increase  being 
greater  than  here  shown  for  wires  larger  than  No.  0  and  less 
for  smaller  sizes.  In  figure  30  is  given  the  curve  showing  the 
increase  in  resistance  for  the  various  sizes  of  copper  wire  in 
the  B.  &  S.  gauge  at  a  frequency  of  500,000  cycles  per  second. 
Thus  a  wire  as  small  as  No.  35,  B.  &  S.,  has  very  nearly  the 
same  resistance  at  this  frequency  as  at  a  steady  current,  or, 

frequency  SOOOOO  


35 


30 


15 


10 


!  = 


t-0 


30 


0  5  10  15  20  25 

<3/zes  of  wires:— B.  &  S.  Gauqe 

FIG.  30.-RESISTANCE  CURVE  SHOWING  INCREASE  FOR  THE  VARIOUS 
SIZES  OF  COPPER  WIRE  IN  THE  B.  &  S.  GUAGE 

in  other  words,  the  thickness  of  the  skin  at  this  frequency  is 
about  equal  to  the  radius  of  the  wire.  In  order  to  be  able  to 
include  all  sizes  of  wire  at  all  frequencies  it  is  evident  that  a 
large  number  of  curves  or  an  extensive  table  of  resistance  and 
frequency  would  be  necessary. 

If  a  large  number  of  wires,  the  diameter  of  which  is  such 
that  the  current  just  penetrates  to  the  center  at  any  given 
frequency,  is  used  in  parallel  in  the  form  of  a  compactly 
stranded  wire  or  cable  it  is  evident  that  all  the  copper  is  in 


RADIOTELEGRAPH?  341 

use  and  that  the  current-carrying  surface  of  such  a  cable  is 
very  much  greater  than  that  of  a  solid  wire  of  the  same  outside 
diameter,  and  hence  the  resistance  is  very  much  lower.  Each 
wire  must,  however,  be  separately  insulated,  as  otherwise  the 
current  will  immediately  seek  the  outer  surfaces  of  the  outer 
wires  on  account  of  the  skin  effect,  and  the  resistance  will  riot 
be  much  decreased  from  that  of  a  solid  wire.  Such  a  stranded 
wire  or  cable,  with  its  individual  wires  separately  insulated,  as 
with  enamel,  is  sometimes  called  litzendraht,  from  the  German 
word.  The  size  of  the  insulated  wire  depends  upon  the  fre- 
quencies at  which  it  is  to  be  used.  If  the  highest  frequency 
should  be  500,000  cycles  per  second,  then  from  figure  30  it  is 
evident  that  there  would  be  but  little  gain  in  using  a  wire 
smaller  than  No.  34  or  No.  35  on  B.  &  S.  gauge.  The  number 
of  wires  depends  upon  the  current  to  be  carried  and  the  resist- 
ance desired.  For  small  currents  it  is  generally  a  multiple  of 
7,  as  7  X  7,  or  49  wires,  but  for  heavy  currents  the  number  may 
be  in  the  hundreds  or  even  in  thousands. 

It  is  evidently  impossible  to  get  a  continuously  variable 
inductance  by  a  sliding  clip  or  contact  on  all  the  wires  of  a 
litzendraht  coil,  so  that  when  such  an  inductance  of  low  resist- 
ance is  desired  it  is  generally  made  in  the  form  of  a  variometer 
wound  with  litzendraht. 

The  use  of  litzendraht  is  not  confined  to  transmitting  coils, 
but  is  also  used  in  receiving  sets  to  get  low-resistance  circuits. 

SPARK    GAPS 

The  function  of  the  gap  is  to  serve  as  a  trigger  in  starting 
the  oscillations  and  to  limit  the  potential  applied  to  the  con- 
densers by  the  transformer  secondary.  An  ideal  gap  would  be 
one  having  an  infinite  resistance  during  the  charging  of  the 
condensers  and  a  zero  resistance  during  each  wave  train  of 
the  discharge. 

The  types  of  spark  gaps  in  use  differ  nearly  as  much  as  the 
other  parts  of  the  closed-circuit  elements.  In  small-sized  sets 
the  electrodes  or  terminals  are  generally  made  of  zinc  or  brass, 
the  sparking  surfaces  being  either  balls  of  one-half  inch 
diameter  or  more,  or  else  rounded  surfaces.  Sharp  points  are 
not  used,  as  at  small  separations  the  potential  required  to 
break  down  the  gap  is  too  small  to  allow  any  considerable 
power  to  be  used,  and  if  the  gap  is  opened  to  increase  the 
potential  and  power  the  gap  resistance  becomes  too  high.  As 
the  power  delivered  to  the  transformer  is  increased  it  is  soon 
found  that  the  discharge  at  the  gap  becomes  flaming  in  charac- 
ter and  has  a  hissing  sound,  seeming  to  be  more  like  an  arc 


342  MILITARY  SIGNAL  CORPS  MANUAL 

than  a  spark,  and  the  gap  terminals  become  very  hot.  The 
reason  for  this  is  that,  owing  to  the  great  quantity  of  elec- 
tricity discharged  across  the  gap,  the  resistance  becomes  so 
low  that  a  high-potential  alternating-current  arc,  which  is 
almost  a  short  circuit,  is  maintained  at  the  transformer  second- 
ary terminals.  This  arc  is  formed  in  the  heated  air  and  the 
vapor  of  the  metals  forming  the  gap  terminals.  Experiment 
has  shown  that  a  blast  of  air  across  or  through  the  gap  will 
blow  out  the  arc  but  not  the  spark.  By  thus  removing  the 
short  circuit  the  condenser  can  be  charged  to  the  full  potential 
of  the  secondary  and  the  power  of  the  set  increased — in  some 
cases  it  may  be  nearly  doubled. 

The  air  blast  may  be  obtained  from  a  blower  or  compressor 
driven,  for  example,  by  an  electric  motor  or  directly  by  the 
rotating  of  the  gap  terminals  themselves,  in  which  case  it  is 
known  as  a  rotating  gap.  There  are  two  general  types  of 
rotating  gaps,  in  the  first  of  which  the  rotation  is  simply  a  con- 
venient means  of  giving  the  necessary  ventilation  and  cooling. 
It  is  not  necessary  that  it  be  provided  with  rotating  terminals, 
although  it  may  be  so  provided.  In  one  of  the  early  types  used 
in  the  Signal  Corps,  shown  in  figure  31,  a  rotating  disk  is  used 


FIG.    31.— NON- SYNCHRONOUS    ROTATING    SPARK    GAP 

between  two  fixed  terminals.  In  this  case  the  sparks  shift  from 
place  to  place  on  the  edges  of  the  disk  as  it  turns,  the  ventila- 
tion being  by  means  of  fans  on  the  face  of  the  disk,  which  blow 
the  air  away  from  the  gaps.  As  no  attempt  is  made  to  secure 
any  special  time  relation  between  the  discharges  and  the 
alternator  frequency  this  type  of  gap  is  often  called  a  non- 
synchronous  gap. 

In  the  second  type  of  rotating  gap  one  set  of  electrodes  is 
attached  to  the  alternator  shaft,  preferably  insulated  from  it, 
and  thus  rotates  at  the  same  speed  as  the  armature;  the  other 
terminal  is  mounted  so  as  to  be  capable  of  adjustment,  both  in 
the  direction  of  rotation  and  in  a  radial  direction.  If  the 
spacing  of  the  revolving  terminals  is  such  that  as  many  ter- 
minals pass  the  fixed  terminal  per  second  as  there  are  alterna- 


RADIOTELEGRAPH?  343 

tions  per  second,  and,  further,  if  the  adjustments  of  potential, 
etc.,  are  such  that  the  discharge  is  at  the  peak  of  each  alterna- 
tion, then  there  will  be  as  many  sparks  per  second  as  there 
are  alternations,  and  the  gap  is  called  a  synchronous  gap. 

In  order  to  secure  the  correct  adjustments  of  a  synchronous 
gap  the  fixed  terminal  should  be  adjusted  radially  to  give  only 
a  small  clearance,  as  1/32  inch  or  less,  and  then  adjusted  in 
the  direction  of  rotation  as  follows :  If  the  rotating  terminals 
are  watched  by  the  light  of  the  sparks  themselves,  they  will 
appear  either  to  be  wavering  back  and  forth  or  else  to  be 
nearly  fixed  in  position.  In  the  former  case  the  discharge  does 
not  occur  at  the  peak  of  the  wave,  but  perhaps  before  the  peak 
in  one  alternation  and  after  in  the  next,  and  hence  the  wavering 
appearance;  in  the  latter  case  the  discharge  is  at  the  peak  of 
the  wave  as  shown  by  the  apparent  steadiness  of  position.  At 
the  same  time  that  this  correct  adjustment  is  secured  the  note 
of  the  spark  as  heard  either  in  the  station  itself  or  at  a  distant 
receiving  station  will  become  much  clearer,  the  advantages  of 
which  will  be  mentioned  later. 

As  it  is  generally  best  not  to  have  long  leads  from  the  spark 
gap  to  the  other  elements  of  the  closed  circuit,  It  may  be  neces- 
sary to  have  all  of  the  closed  circuit  as  well  as  the  open  circuit 
in  the  room  with  the  alternator,  in  which  case  the  operator 
and  the  receiving  set  should  be  in  another  room.  In  some 
cases  it  may  be  possible  to  mount  the  alternator  and  gap  so 
that  short  leads  can  be  brought  out  from  the  latter  through 
well-insulated  bushings  into  the  next  room,  which  should  be 
sound  proof,  and  thus  all  the  circuits  be  contained  in  the  same 
room  with  the  operator  for  convenience  and  promptness  in 
making  changes  in  wave  length  and  other  adjustments,  etc. 

QUENCHED    SPARK    GAPS 

Most  modern  sets  use  the  quenched  spark  gap,  a  brief 
description  of  which  will  be  given  here  and  the  theory  of  the 
quenched  spark  transmitter  later.  The  g:  p  is  essentially  a 


FIG.   32.— SECTION   OF   PLATES  OF  QUEXCHED   GAP 

series  gap  consisting  of  a  number  of  plates  with  small  separations 
between  the  sparking  surfaces,  which  are  inclosed  in  air-tight 
chambers  formed  between  the  plates  themselves. 


344 

In  figure  32  is  shown  a  section  of  a  gap  where  P  are  the 
plates,  often  made  of  copper,  which,  on  account  of  good  con- 
ductivity for  heat,  will  carry  off  the  heat  of  the  spark ;  F  are 
the  flanges,  which  help  the  cooling  by  exposing  a  large  area 
to  the  air  or  to  the  air  blast  to  be  mentioned  later;  S  are  the 
sparking  surfaces  between  which  the  sparks  pass,  which  may 
be  of  the  same  copper  stock  as  the  rest  of  the  plate  or  of  heavy 
silver  plate  fastened  in  place  at  S;  M  the  separators. or  insulat- 
ing rings,  also  called  gaskets,  between  the  plates,  often  made 
of  mica,  about  0.010  inch  thick  (10  mils),  the  thickness  of  which 
determines  the  distances  between  the  sparking  surfaces. 
In  some  cases  the  separators  are  made  of  rubber  or  other  insulating 
materials  which  are  somewhat  compressible,  and  then  the  bear- 
ing surfaces  are  often  corrugated,  as  shown  in  figure  33,  so 
that  the  material  may  be  pressed  down  into  the  annular  spaces. 
Whatever  the  type  of  separator,  the  gap  as  a  whole  must  be 
put  under  strong  mechanical  pressure  so  that  the  air  shall  be 
excluded  from  the  sparking  surfaces,  the  reason  for  which 
seems  to  be  that  these  surfaces  are  roughened  with  free  expos- 
ure to  air,  and  an  arc  is  formed  at  some  point  which  behaves 
as  a  short  circuit  between  the  plates  and  lowers  the  efficiency 


F  S 

FIG.   33.— QUENCHED   GAP   PLATES  WITH   CORRUGATED   SURFACES 

of  the  gap.  Gaps  with  mica  separators  should  not  be  com- 
pressed as  tightly  as  the  others  because  the  mica  will  be  injured 
by  the  excessive  pressure  and  the  heat  from  the  gap  and  will 
soon  crack  and  puncture.  In  order  to  keep  the  gap  cool  the 
flanges  of  the  plates  are  generally  blackened,  as  a  black  body 
will  cool  more  quickly  than  a  polished  body,  other  things  being 
equal.  In  the  larger-sized  sets  it  is  necessary  to  cool  the  gap 
by  means  of  a  blower  driven  by  a  motor  similar  to  the  type 
used  in  blowing  out  the  arc  of  an  open  gap.  The  potential 
between  each  plate  of  a  gap  assembled  as  above  is  about  1,000 
volts.  This  may  be  measured  by  finding  the  potential  across 
several  gaps  by  means  of  the  needle  gap  and  the  values  in 
Table  1,  and  then  dividing  this  potential  by  the  number  of 
the  gaps. 

Under  service  conditions  a  quenched  gap  should  be  taken 
apart  only  when  it  is  absolutely  certain  that  trouble  in  the 
radio  circuits  has  been  located  in  the  gap  itself,  as  shown,  for 
example,  by  one  or  two  of  the  plates  becoming  much  hotter 


RADIOTELEGRAPHY  345 

than  the  others,  or  by  an  actual  puncture  of  a  gasket  or  sep- 
arator. The  reason  for  not  taking  the  gap  apart  frequently 
seems  to  be  that  after  a  certain  time,  depending  on  the  amount 
of  use,  the  oxygen  of  the  air  contained  between  the  plates 
becomes  inactive  and  there  is  no  tendency  of  the  sparks  to 
roughen  the  sparking  surfaces  and  form  local  arcs,  but  rather 
that  these  surfaces  are  worn  smooth  and  kept  bright  by  the 
sparking  action.  If,  however,  the  gaps  are  continually  being 
taken  apart  air  will  be  admitted  each  time,  and  the  gap  may 
not  give  the  results  that  otherwise  would  be  attained.  There 
are  cases  where  quenched  gaps  have  been  used  handling  heavy 
traffic  daily  for  six  months  or  more  without  the  necessity  of 
being  taken  apart  once  during  that  time,  and  in  one  of  the 
Signal  Corps  sets  such  a  gap  has  now  been  in  service  for  nearly 
three  years  without  having  a  plate  or  gasket  replaced  or  even 
the  gap  taken  apart.  If,  however,  it  becomes  necessary  to 
clean  the  plates,  they  should  be  laid  face  down  on  fine  emery 
cloth  or  paper  on  a  flat  surface  and  the  roughness  carefully 
smoothed  off.  When  mica  is  used  as  a  separator,  the  bearing 
surface  is  generally  flush  with  the  sparking  surface,  and  par- 
ticular care  must  be  taken  to  keep  the  two  plane  and  parallel 
as  shown  by  a  straightedge.  Any  irregularities  on  the  bearing 
surface  will  admit  air  and  injure  the  gap,  no  matter  what  pres- 
sure may  be  put  on  the  plates.  Almost  all  gaps  are  provided 
with  more  plates  than  should  be  used  under  service  conditions, 
the  extra  gaps  being  short-circuited  by  clips  for  that  purpose, 
so  that  when  any  one  gap  becomes  bad  it  can  be  temporarily 
cut  out  of  circuit  without  the  necessity  of  taking  the  whole  gap 
apart. 

CONNECTION  OF  CLOSED  OSCILLATING  OR  PRIMARY  CIRCUIT 
WITH   ANTENNA   CIRCUIT 

In  the  original  transmitting  arrangement  of  Marconi  the 
spark  gap  was  inserted  between  the  antenna  and  ground,  the 
transformer  secondary  terminals  being  connected,  one  to  the 
antenna  and  the  other  to  the  ground,  as  shown  in  figure  34. 
This  circuit  is  often  known  as  the  plain  Marconi  antenna  or 
aerial.  As  the  antenna  has  both  inductance  and  capacity  it 
forms  in  this  case  the  oscillating  circuit,  taking  the  place  of 
the  circuit  CSL  of  figure  19.  The  values  of  the  inductance  and 
the  capacity  vary  with  the  size,  shape,  etc.,  of  the  antenna; 
thus  for  a  small  antenna,  as  on  an  artillery  tug  or  in  a  port- 
able field  set,  the  capacity  may  be  between  0.0006  and  0.0009  mf., 
and  the  inductance  between  20,000  and  30,000  cms.,  or  0.02  and 
0.03  millihenrys ;  and  for  a  "T"  or  inverted  "L"  antenna  on 
180-foot  masts,  the  capacity  may  be  as  large  as  0.0015  or 
0.0020  mf.,  and  the  inductance  30.000  to  60.000  cms.  or  0.030  to 


MILITARY  SIGNAL  CORPS  MANUAL 


0.060  millihenrys.      Only  in  the  largest  stations  is  the  capacity 
of  the  antenna  as  large  as  0.01  mf. 

From  its  position  and  shape  the  antenna  circuit  is  often 
called  the  open  or  radiating  circuit,  as  distinguished  from 
the  closed  oscillating  or  primary  circuit.  It  is  a  good  radiator 
of  the  electrical  energy  imparted  to  it  by  the  transformer,  but 
its  small  capacity  makes  it  impossible  to  store  a  large  charge 
in  it,  and  consequently  at  each  discharge  across  the  gap  there 
is  comparatively  little  energy  available  for  radiation.  For  this 


o 
o 


FIG.  34.— CIRCUIT  OF  THE   PLAIN   MARCONI  AERIAL 

and  other  reasons  to  be  mentioned  later  this  circuit  is  not  now 
used  in  practical  radiotelegraphy. 


COUPLING 

By  means  of  the  arrangement  shown  in  figure  35  a  large 
charge  may  be  stored  in  condenser  C,  much  larger  than  that 
which  can  be  stored  in  antenna  of  figure  34,  and  the  discharge 
of  this  condenser  through  the  gap  S  and  the  inductance  L  will 
produce  powerful  oscillations  in  the  closed  oscillating  or 
primary  circuit.  On  account  of  its  position  and  shape,  how- 
ever, this  closed  oscillating  circuit  is  a  poor  radiator  of  elec- 
trical energy.  There  are  two  general  ways  in  which  the  energy 
of  this  circuit  can  be  transferred  to  the  antenna  circuit;  or,  as 
it  is  said,  two  ways  of  coupling  the  circuits.  One  is  shown  in 
figure  36,  where  the  ground  and  the  antenna  circuits  are  directly 
connected  to  the  inductance  coil  of  the  closed  circuit,  and  the  cir- 
cuits are  said  to  be  directly  connected,  directly  coupled,  or  condiic- 


RADJOTELEGRAPHY 


347 


lively   couplca.     From  its  position   in   the  circuit  the  coil  is  often 
called  the  antenna  coil  or  helix.    The  other  is  shown  in  figure  35, 


A. 

i 


FIG.   3S.-INDUCTIVELY  COUPLED   CIRCUIT 

where  a  number  of  turns  in  the  antenna  coil  La,  connected  between 
the  antenna  and  ground,  is  brought  near  enough  to  a  number  of 
turns  of  the  coil  Li  in  the  closed  oscillating  circuit  to  have  oscilla- 


FIG.   36.— DIRECTLY   COUPLED   CIRCUIT 


348 


MILITARY  SIGNAL  CORPS  MANUAL 


tions  induced  in  the  antenna  coil  and  circuit,  and  the  two  circuits 
are  said  to  be  inductively  coupled  or  connected.  The  two  coils 
Li  and  L^  form  an  oscillation  transformer,  as  it  is  usually  called,  the 
coil  Li  being  the  primary  and  coil  La  the  secondary.  Hence  the  an- 
tenna circuit  is  sometimes  called  the  secondary  circuit  as  well  as  the 
open  or  radiating  circuit,  as  previously  mentioned.  There  is  no 
essential  difference  in  the  operation  or  efficiency  of  the  transfer  of 
energy  in  the  two  types  of  coupling,  but  rather  that  each  may 
have  advantages  in  certain  cases.  Thus  the  directly  connected 
set  is  somewhat  more  compact  and  the  inductively  coupled  set 
somewhat  more  easily  adjusted  under  certain  conditions. 

In  direct  connected  sets  when  nearly  the  same  turns  are 
connected  in  both  the  primary  and  the  secondary  circuits — that 
is,  when  most  of  the  turns  in  use  are  common  to  both  circuits, 
as  shown  in  figure  37 — the  coupling  is  said  to  be  close  or  tight. 


FIG.    37.— CLOSE    COUPLED    CIRCUIT 

When  only  a  comparatively  few  turns  are  common  to  the  two 
circuits,  as  shown  in  figure  38,  the  coupling  is  said  to  be  loose. 
Similarly  in  inductively  connected  sets,  when  most  of  the  turns 
in  use  in  the  two  circuits  are  near  together,  as  when  one  coil  is 
moved  inside  the  other,  as  shown  in  figure  39,  the  coupling  is 
close.  When  the  turns  in  use  are  not  near  together,  as  shown  in 
figure  35,  the  coupling  is  loose.  In  the  case  of  inductively 
coupled  sets  it  is  evident  that  moving  the  coils  of  the  oscillation 


RADIOTELEGRAPHY 


349 


transformer  nearer  together  will  tighten  the  coupling  or  make 
it  closer,  and  vice  versa,  moving  the  coils  further  apart  will 
loosen  the  coupling.  If  the  turns  in  use  in  either  circuit  of  a 
directly  connected  set  are  moved  so  as  to  have  few  or  even 
no  turns  at  all  in  common,  as  shown  in  figure  38,  the  coupling 


FIG.  38.-LOOSE  COUPLED  CIRCUIT 

is  loosened.  The  coupling  may  be  made  loose  in  other  ways, 
one  of  which  is  illustrated  in  figure  40,  where  the  coil  Ly2 
often  known  as  a  loading  coil,  is  inserted  in  the  antenna  circuit, 
thereby  adding  inductance  not  coupled  with  the  primary 
circuit.  Similarly  in  the  case  of  inductively  connected  sets 


350 


MILITARY  SIGNAL  CORPS  MANUAL 


the  coupling  may  be  loosened  by  inserting  the  loading  coil  L/a 
in  the  antenna  circuit,  as  shown  in  figure  41.  In  both 
these  cases  it  is  to  be  noted  that  the  result  is  practically 
the  same  as  though  the  turns  in  use  in  the  two  circuits 


FIG.   39.— CLOSE   COUPLED   CIRCUIT 

were  moved  farther  apart  as  a  whole.  In  both  the  directly 
connected  and  the  inductively  connected  sets  the  coupling  may 
also  be  loosened  by  inserting  a  loading  coil  in  the  primary 
circuit,  as  shown  in  one  case  in  figure  42.  By  means  of  these 
loading  coils  a  directly  connected  set  can  thus  be  made  as 
loosely  coupled  for  practical  work  as  an  inductively  connected 


RADIOTRLECRAniY 


351 


set.  In  such  a  circuit  as  that  in  figure  40,  the  coil  which  is 
common  to  both  circuits  and  serves  to  transfer  the  energy  from 
one  to  the  other  is  sometimes  called  the  coupling  coil.  At  the 


FIG.   40.— LOADING   COIL   IN   ANTENNA   CIRCUIT 


present  time  most  of  the  sets  in  use  in  the  Signal  Corps  are 
loosely  coupled  and  all  of  the  various  methods  of  obtaining 
loose  coupling  here  described  are  in  use,  each  one  having 
advantages  in  its  particular  radio  set. 


352 


MILITARY  SIGNAL  CORPS  MANUAL 


I 
1 


FIG.  41.— ANOTHER  HOOK-UP  OF  FIGURE  40 
ANTENNA 

The  open  or  radiating  circuit  has  its  own  natural  period  of 
oscillation  expressed,  as  in  the  case  of  the  closed  circuit,  in 
fractions  of  a  second.  The  most  energy  can  be  delivered  to  it 
from  the  closed  oscillating  circuit  when  by  adjusting  the  induc- 
tance or  capacity,  or  both,  of  the  latter  the  oscillations  in  it 
have  the  same  frequency  as  in  the  open  circuit;  that  is,  until 
the  two  circuits  are  in  resonance.  Then  the  strongest  oscilla- 
tions or  the  greatest  current  will  be  flowing  in  the  antenna  as 
shown  by  the  maximum  reading  in  a  hot-wire  ammeter  of 
figures  37  to  42,  inclusive.  The  ammeter  is  usually  connected 


KA  D I OT 11 LEGRAPH  Y 


353 


between  the  ground  and  the  secondary  of  the  oscillation  trans- 
former, but  may  be  connected  between  the  secondary  and  the 
antenna. 

These  powerful  damped  high-frequency  oscillations  in  the 
antenna  or  open  circuit  produce  corresponding  periodic  dis- 
turbances in  the  surrounding  medium,  which  spread  outward 
in  the  form  of  electromagnetic  waves,  as  has  already  been 
explained. 

In  general  the  higher  the  antenna,  the  greater  the  energy 


•w/www 


FIG.    42.— LOADING    COIL   IN  PRIMARY    CIRCUIT 

in  the  form  of  electromagnetic  waves  which  it  can  radiate  and 
receive ;  in  other  words,  the  greater  the  distance  to  which  it 
can  send  and  receive  signals.  In  most  cases  a  large  capacity 
is  also  desired,  which  can  be  secured  by  putting  up  a  number 
of  wires,  but  there  is  little  gain  in  capacity  unless  the  wires 
are  at  least  a  foot  apart.  Additional  capacity  and  increased 
efficiency  in  radiation  can  be  secured  by  using  a  flat  top  or 
horizontal  spread  of  wires  at  the  top  of  the  mast,  which 
becomes,  as  it  were,  one  plate  of  a  condenser,  the  earth  being 
the  other  plate,  with  the  air  as  the  insulator  or  dielectric. 
Antennae  are  often  divided  into  three  types,  depending  on  the 
way  in  which  the  wires  are  arranged  at  the  top,  such  as 


354 


MILITARY  SIGNAL  CORPS  MANUAL 


umbrella,  inverted  L,  and  T,  where  the  names  are  sufficiently 
suggestive  as  not  to  require  a  description.  The  umbrella  is  best 
adapted  for  short  stations  having  a  single  mast  or  tower  with 
several  acres  of  land  around  the  station,  and  has  largely  been  used 
by  the  Signal  Corps. 


FIG.  43.— THE  SIGNAL  CORPS  AERIAL  INSTALLATION  AT 
FAIRBANKS,  ALASKA 


RADIOTELEGRAPHY 


355 


The  inverted  L  and  the  T  can  be  installed  on  shipboard  or  at 
shore  stations,  but  require  two  masts  or  towers.  In  the  case 
of  the  umbrella  antenna,  the  wires  extending  outward  from  the 
mast  should  be  kept  as  nearly  horizontal  as  possible  and  as  far 
away  from  tree  tops,  buildings,  roofs,  etc.,  as  circumstances  will 
permit.  The  distant  ends  are  dead-ended  at  high-potential 
insulators  attached  to  long  guys  carried  out  to  stub  masts  or 
deadmen.  These  guys  should  have  insulators  inserted  every 


Antenna  resistance:—  Ohms 


Funo  zment  il 


FIG.    44.-WAVE    CURVE   OF   TYPICAL   ANTENNA   RESISTANCE 

50  or  100  feet  to  prevent  them  from  serving  as  extensions  to 
the  antenna  wires  and  thereby  bring  the  antenna  too  near  the 
ground.  It  is  not  necessary  that  the  antenna  wires  be  sym- 
metrically arranged  around  the  tower,  it  being  far  more 


356  MILITAR  Y  SIGNAL  CORPS  MAN  I '  AL 

important  that  advantage  be  taken  of  the  configuration  of  the 
ground  and  that  the  outer  ends  be  kept  well  elevated.  This  is 
shown  in  the  plan  of  the  Signal  Corps  radio  installation  at 
Fairbanks,  Alaska,  figure  43,  where,  on  account  of  swampy 
land  along  the  river  near  the  station,  a  symmetrical  arrange- 
ment is  practically  impossible. 

The  antenna  must  be  well  insulated,  particularly  at  the  outer 
ends  of  the  horizontal  wires,  as  otherwise  there  will  be  leakage 
to  ground  in  damp  weather  or  rainy  seasons,  which  will  cause 
a  serious  loss  in  efficiency  when  the  station  is  transmitting. 
High-tension  insulators  of  electrose  or  porcelain  are  usually 
furnished  for  use  at  these  points  of  the  circuit. 

The  antenna  wires  are  generally  stranded,  thus  giving  some- 
what greater  strength  than  a  solid  wire  of  the  same  weight. 
For  permanent  stations  a  phosphor-bronze  or  silicon-bronze 
wire  is  generally  used  consisting  of  seven  strands  of  either  No. 
20  or  No.  14  B.  &  S.  gauge,  and  for  the  portable  stations,  such 
as  the  Signal  Corps  field-pack  sets,  an  antenna  cord  made  up 
of  42  phosphor-bronze  wires  stranded  around  a  hempcord 
center.  A  very  low  resistance  in  the  antenna  wires  is  not  as 
nesessary  as  it  might  seem  to  be,  as  it  has  been  shown  by 
theory  and  proven  by  experiment  that  the  radiation  of  electro- 
magnetic waves  introduces  a  resistance,  sometimes  called  the 
radiation  resistance,  which  in  general  is  many  times  the  high- 
frequency  resistance  of  the  wires  themselves.  This  radiation 
resistance  rarely  falls  below  2  ohms  on  a  ship  set  and  may  be 
as  high  as  20  or  30  ohms  in  a  shore  station.  When  the  antenna 
resistance  is  measured  under  service  conditions  it  includes  that 
of  the  wires  at  the  given  frequency,  the  resistance  of  the 
ground,  and  that  due  to  the  radiation  of  energy,  the  latter  being 
generally  the  larger  part.  A  typical  antenna  resistance  is 
shown  in  figure  44,  where  it  is  to  be  noted  that  the  resistance  is 
greatest  near  the  fundamental  wave  length  of  the  antenna  and 
is  least  at  a  wave  length  about  one  and  one-half  or  two  times  the 
fundamental.  It  is  at  or  near  this  point  that  many  stations  work 
most  efficiently. 


ARTIFICIAL    ANTENNA 

In  many  cases  it  is  convenient  to  make  station  tests  without 
using  the  actual  antenna,  particularly  where  such  use  would 
cause  unnecessary  interference.  A  local  circuit  of  a  coil  L  and 
condenser  C  having  the  same  inductance  and  capacity  as  the 
antenna  and  called  an  artificial  antenna  is  often  used,  thus 
serving  the  same  purpose  as  an  artificial  line  or  cable  in  tele- 
graph tests.  When  a  resistance  R  is  inserted  in  this  circuit  to 


RADIOTELEGRAPH? 


357 


give  the  same  current  as  actually  flows  in  the  antenna  this 
resistance  is  approximately  equal  to  the  antenna  resistance. 
The  circuit  for  making  these  measures  is  shown  in  figure  45, 
where  the  circuit  of  L,  C,  and  R,  which  replaces  the  antenna 
when  the  switch  is  thrown  to  the  right,  is  the  artificial  antenna. 


FIG.    45.— ARTIFICIAL    ANTENNA    CIRCUIT 

The  antenna  inductance  L  and  capacity  C  can  be  easily 
measured  with  the  help  of  a  wave  meter  and  thus  a  suitable 
coil  and  condenser  selected  for  use  in  the  artificial  antenna 
which  will  then  closely  represent  the  actual  antenna. 


EFFICIENCY   OF   RADIO   SET 

The  antenna  resistance,  the  radiation  resistance,  and  the 
antenna  current  all  change  as  the  frequency  or  wave  length 
changes.  If  at  any  one  frequency  or  wave  length  the  square 
of  the  antenna  current  in  amperes  is  multiplied  by  the  antenna 
resistance  in  ohms,  the  product,  PR,  is  in  watts,  and  represents 
the  power  delivered  by  the  closed  oscillating  circuit  to  the 
antenna;  that  is,  it  is  the  antenna  input,  as  it  is  sometimes 
called,  or  the  ivatts  in  the  antenna.  If  the  number  of  watts 
delivered  by  the  alternator  is  known,  the  efficiency  from  alter- 


358  MILITARY  SIGNAL  CORPS  M.  l\(  'AL 

nator  to  antenna  can  be  found  by  finding  the  quotient  of  the 
watts   in   antenna   divided  by  the   watts   from  the   alternator, 

~  .  watts  in  antenna 

thus  Q  =  efficiency  = 


watts  from  alternator. 

In  the  early  types  of  spark  sets  this  value  was  as  low  as  10  or 
20  per  cent,  whereas  in  modern  quenched  spark  sets,  it  may 
be  as  high  as  50  per  cent  or  even  higher.  If  a  motor-generator 
set  is  used  and  the  number  of  watts  delivered  to  the  motor  is 
known,  the  over-all  efficiency  can  similarly  be  found  by  dividing 
the  antenna  watts  by  the  motor  watts,  thus  over-all 

antenna  watts.          ^, 

(^  =  The     percentage     so     obtained     will     of 

motor  watts. 

course  be  lower  than  before,  as  it  allows  for  losses  in  the 
motor-generator  which  were  not  considered  in  the  previous 
case. 

The  rating  of  the  earlier  radio  sets  was  given  as  the  output 
of  the  alternator,  but  in  modern  sets  it  is  often  given  as  the 
number  of  watts  delivered  to  the  antenna.  In  the  latter  case 
the  artificial  antenna  may  be  used  and  its  inductance,  capacity, 
resistance,  together  with  the  current  and  watts  at  a  given 
wave  length  must  then  be  specified. 

When  steel  towers  are  used  they  are  generally  heavily 
insulated  at  the  base,  but  provided  with  switches  for  grounding 
when  desired,  as  during  lightning  storms,  etc.  In  some  cases 
the  station  becomes  more  efficient  in  transmitting  if  the  tower 
is  grounded.  In  general,  however,  the  result  of  grounding  can 
be  told  only  by  tests  at  the  receiving  station  of  the  loudness  of 
the  signals,  and  not  by  the  readings  of  the  antenna  hot-wire 
ammeter  or  other  means  at  the  transmitting  station.  The 
grounding  of  the  tower  generally  makes  it  necessary  to  change 
the  tuning  of  the  transmitter,  and  there  are  corresponding 
changes  in  the  reading  of  the  antenna  ammeter,  but  increases 
in  its  reading  do  not  necessarily  mean  increases  in  the  signals 
at  the  receiving  station,  as  part  of  this  increase  is  due  to 
increased  flow  of  current  through  the  tower  to  ground.  It  is 
for  this  reason  that  the  results  of  grounding  should  always 
be  tested  at  the  receiver. 


GROUND 

An  efficient  ground  for  a  radio  station  is  very  different  from 
that  used  at  an  ordinary  telegraph  station.  The  latter  gener- 
ally has  a  metal  plate  set  deep  in  wet  ground,  but  the  former 


RADIOTELEGRAPH Y  359 

needs  a  large  spread  on  the  surface  or  just  under  it.  Thus, 
instead  of  using  a  large  copper  plate  or  rods  close  together,  a 
far  better  type  of  ground  would  be  to  use  wires  radiating  out 
from  the  station,  or  to  duplicate  the  umbrella  or  flat-top 
antenna  system  a  short  distance  under  the  surface  of  the 
ground.  The  advantages  of  a  surface  ground  may  be  under- 
stood when  it  is  remembered  that  close  to  the  station  the  mag- 
netic and  static  fields  are  very  intense,  so  that  if  they  had  to 
pass  down  through  the  earth  to  a  ground  plate  instead  of  being 
able  to  travel  wholly  on  the  surface,  as  shown  in  figure  9,  there 
would  be  introduced  an  additional  ground  resistance  and  local 
earth  currents  would  be  caused,  with  corresponding  losses. 
The  use  of  a  surface  ground  serves  to  reduce  these  losses  to  a 
minimum.  It  should  be  noted  that  the  instantaneous  values  of 
the  transmitting  currents  are  very  large  and  the  frequencies 
are  very  high,  sometimes  a  million  or  more  per  second,  so  that 
considerable  copper,  such  as  stranded  wires  or  copper  strip, 
should  be  used  both  in  the  ground  wires  and  in  the  leads  con- 
necting the  set  to  them. 

Another  type  of  ground  connection  which  has  been  success- 
fully used  at  permanent  stations,  and  also  in  the  portable  field 
sets,  is  known  as  the  counterpoise.  In  the  permanent  stations 
this  consists  of  a  set  of  bare  horizontal  radial  or  parallel  wires, 
which  are  supported  by  insulators  on  posts  7  feet  or  more  above 
ground.  A  counterpoise  of  a  fan  type  has  been  installed  at 
Fort  Sam  Houston,  Tex.,  in  which  bare  wires,  No.  10,  B.  &  S. 
gauge,  190  feet  long,  extend  outward  from  the  station  under 
the  antenna,  being  spaced  6  feet  apart  at  the  station  and  20 
feet  at  the  distant  ends.  A  counterpoise  of  the  radial  type 
has  been  installed  at  the  Fairbanks  (Alaska)  station,  as  shown 
in  figure  43,  where  the  wires  are  bare,  hard-drawn  copper  No. 
12,  B.  &  S.,  about  210  feet  long,  and  spread  out  in  two  arcs, 
each  of  90  degrees.  A  counterpoise  is  particularly  efficient  in 
case  the  soil  is  dry,  as  at  Fort  Sam  Houston,  and  also  where 
there  is  a  heavy  snowfall,  as  at  Fairbanks.  At  the  latter  sta- 
tion both  a  ground  and  a  counterpoise  have  been  installed.  In 
the  case  of  the  Signal  Corps  wagon  sets,  radial  counterpoise 
wires  mounted  on  temporary  poles,  carried  as  part  of  the  set, 
were  used  at  first,  but  now  have  been  replaced  by  the  same 
type  as  that  of  the  pack  sets,  which  consist  of  rubber-covered 
wires,  each  100  feet  long,  laid  out  radially  on  the  ground. 
Although  not  directly  connected  with  the  ground  at  all,  these 
wires  really  constitute  one  plate  of  a  condenser,  the  ground 
"being  the  other. 


360 


MILITARY  SIGNAL  CORPS  MANUAL 


WAVE   LENGTHS 

Before  describing  the  various  receiving  circuits  and  the 
theory  of  their  operation,  some  of  the  terms  applied  to  them 
and  to  the  transmitting  circuits  will  be  denned. 

In  the  mechanical  illustrations  of  damped  oscillations  and 
resonance,  by  means  of  the  steel  spring  and  the  tuning  forks 
it  was  convenient  to  use  both  the  frequency  expressed  in  the 
number  of  oscillations  per  second  and  the  period  expressed  in 
fractions  of  a  second.  The  same  terms  were  used  in  describ- 
ing the  electrical  oscillations  in  the  radio  circuits,  and  although 
this  usage  is  entirely  correct,  it  is  somewhat  more  common  to 
use  the  term  wave  length,  which  will  be  defined  in  the  follow- 
ing paragraphs. 

At  the  end  of  one  second  of  time  after  an  electromagnetic 
wave  has  begun  to  radiate  from  an  antenna,  it  will  have 
reached  a  point  300,000,000  meters  distant;  that  is,  it  is  said  that 
its  velocity  is  300,000,000  meters  per  second,  or,  as  it  is  often 
abbreviated,  V  =  300,000,000  meters.  During  this  interval  of 
time  the  direction  of  the  magnetic  and  the  static  lines  of  the 
waves  has  been  reversed  very  many  times ;  in  fact,  as  many 
times  as  the  oscillations  in  the  antenna  have  been  reversed. 
Similarly  in  this  interval  of  space  both  fields  will  be  in  the 
same  direction  at  very  many  points,  all  separated  by  equal 
distances,  as  represented  in  figure  9.  The  distance  between 
any  two  such  points  is  called  a  wave  length  and  is  generally 
given  in  meters,  the  symbol  for  which  is  X. 

It  is  evident  that  the  greater  the  number  of  times  per  second 
that  the  two  fields  have  been  reversed  the  shorter  will  be  the 
distance  in  meters  between  the  points  where  the  fields  are  in 
the  same  direction;  that  is,  the  shorter  the  wave  length;  and, 
vice  versa,  the  fewer  the  number  of  times  per  second  that  the 
fields  have  been  reversed,  the  longer  will  be  the  distance 
between  the  points  where  the  fields  are  in  the  same  direction; 

N 

A 


HSSp&i  ""* 

p_— -  —  —  — .  —  —  —  — —  Tim*  =J Second  —  -~- ^~~    j 

!•_ V—3OOOOOOOO  Motor* •*• 

FIG.  46.-WAVE  LENGTH  GRAPHIC  OF  STATIC  FIELD  DIRECTION 


RADIOTELEGRAPHY  361 

that  is,  the  longer  will  be  the  wave  length.  If  N  is  the  number 
of  points  in  the  distance  300,000,000  meters  that  the  fields  have 
the  same  direction,  and  if  X  is  the  wave  length  in  meters,  then 
we  have  the  relation  N  X  *  =  V.  This  is  one  of  the  funda- 
mental relations  in  radiotelegraphy  and  is  shown  graphically 
in  figure  46,  where  to  secure  simplicity  only  the  static  field  is 
indicated,  in  which  it  is  seen  that  the  direction  of  the  field  is 
repeated  N  times  in  the  distance  V  =  300,000,000  meters,  which 
is  traveled  in  one  second  of  time. 

A  short  table  of  wave  lengths  and  frequencies,  computed 
from  the  equation  N  X  ^  =  V,  is  given  below : 

Wave  Frequency 

length  in  oscillations 

in  meters  per  second 

100  3,000,000 

200             1,500,000 

300 1,000,000 

400 750,000 

500 600,000 

600 500,000 

1,000 300,000 

2,000 150,000 

3,000. 100,000 

4,000 75,000 

5000  60,000 

6000 50,000 

10,000 30,000 

From  this  table  and  from  the  relation  T  —  -~-it  is  seen  that  the 

N 

shorter  the  wave  length  the  higher  is  the  frequency  in  number 
of  oscillations  per  second  and  the  shorter  the  period  of  each 
oscillation  in  fractions  of  a  second;  and,  vice  versa,  the  longer 
the  wave  length  the  lower  is  the  frequency  in  oscillations  per 
second  and  the  longer  the  period  of  each  oscillation  in  fractions 
of  a  second. 

Although  the  wave  length  is  rarely,  if  ever,  measured  as  the 
distance  in  space  between  two  points  where  the  electromagnetic 
fields  have  the  same  direction,  yet  it  can  be  very  accurately 
measured  by  other  means.  One  of  these  makes  use  of  the 
relations  N  X  ^  =  V,  and  may  be  briefly  described  as  follows :  It 
consists  in  photographing  the  discharges  in  a  wave  train  at  the 
spark  gap  at  a  very  rapid  but  known  speed.  From  the  speed  of  the 
plate  and  separation  of  the  successive  images  it  is  possible  to 
determine  the  frequency — that  is,  N— and  hence  the  wave  length  X. 


362  MILITARY  SIGNAL  CORPS  MANUAL 

FREQUENCIES  IN   RADIO   MEASUREMENTS 

It  will  be  noted  that  it  has  been  necessary  to  speak  of  the 
frequency  of  circuits  from  two  or  three  different  points  of  view, 
which  will  be  summarized  as  follows:  (i)  The  frequency  of  the 
alternator,  which  depends  upon  the  speed  and  design  of  the  machine, 
as  from  60  to  500  cycles  per  second.  This  frequency  is  independent 
of  all  of  the  radio  circuits.  (2)  The  spark  frequency  or  wave- 
train  frequency,  which  depends  on  the  alternator  frequency,  the 
capacity  of  the  closed-circuit  condenser,  the  voltage  at  the  spark 
gap,  etc.,  as  120  to  500  or  1,000  sparks  or  wave  trains  per  second. 
(3)  The  frequency  of  the  oscillations  in  the  radio  circuits,  which 
depends  only  on  the  capacity  and  inductance  in  the  circuit  in 
question,  as  1,000,000  oscillations  per  second  for  a  wave  length  of 
300  meters,  or  100,000  oscilations  per  second  for  a  wave  length 
of  3,000  meters.  Use  must  be  made  of  all  of  these  frequencies 
in  dealing  with  the  problems  of  radiotelegraphy. 

WAVE    METER 

The  instrument  used  to  measure  the  wave  length  of  the 
oscillations,  and  hence  the  frequency  or  period  as  may  be 
desired,  is  called  a  wave  meter.  It  consists  essentially  of  a  closed 
circuit  of  coil  and  condenser  and  some  means  of  indicating 
resonance  as  a  low  resistance  hot-wire  ammeter.  From  the 


FIG.  47.— AMMETER  IN  CIRCUIT  TO  INDICATE  RESONANCE 

known  values  of  the  inductance  and  capacity  the  frequency  or 
wave  length  can  be  computed  by  the  formulae 


_1 

ZTT  yTC 


and  X  — 


V 


K.I  1)10  Tl-LEGRAPHY  363 

where  the  inductance  L  and  the  capacity  C  must  be  expressed 
in  the  units  of  the  electromagnetic  system,  and  X  will  be  in 
meters  if  v  is  in  meters,  or  v  =  300,000,000.  As  it  may  be  some- 
times more  convenient  to  use  the  units  of  the  practical  system, 
as  microfarads  and  millihenrys,  for  example,  the  formula  will 
also  be  given  for  these  units  as  follows: 

5033          5000 
W—  —  -  =  —  -  —  approximately 

X/LC 


X  =  59600  V  LC~=60000  V  L(T  approximately. 

Thus  if  L  is  0.0352  millihenrys    and    C   is    0.0020   mf.,   L  X  C    is 
0.0000704,   V  0.0000704  is  0.00839,  and  X  is  59600x0.00839  meters. 

5033 
or  is  500  meters.       Similarly  N  is       .Q-     =  600,000  oscillations  per 


second,  which   agrees   with   the   value    in    the   table   previously 
given  for  a  wave  length  of  500  meters. 

In  order  to  include  a  wide  range  of  wave  lengths  or  fre- 
quencies several  coils  are  generally  provided,  which,  in  the 
best  meters,  are  wound  with  litzendraht,  thereby  to  make  the 
high  frequency  resistance  low,  and  hence  the  meter  sensitive 
and  the  tuning  sharp.  The  variable  condenser  has  either  air 
or  oil  for  the  dielectric  rather  than  a  solid  material,  so  that 
there  is  little  or  no  internal  loss.  By  means  of  the  variable 
condenser  the  circuit  can  be  tuned  to  resonance  with  any  cir- 
cuit whose  wave  length  is  desired.  To  indicate  resonance  a 
hot-wire  ammeter  or  wattmeter  may  be  used,  with  a  suitable 
shunt  to  keep  the  resistance  in  circuit  low,  as  shown  in  figure  47, 
where  C  is  the  variable  condenser,  L  the  inductance,  and  A  the 
shunted  ammeter  or  wattmeter.  To  measure  the  wave  length  the 
wave  meter  is  brought  near  the  circuit  in  question,  but  loosely 
coupled  with  it,  and  the  capacity  of  the  condenser  is  varied  until  a 
setting  is  found  that  gives  a  maximum  reading  in  the  hot-wire 
meter.  From  this  setting  and  the  calibration  of  the  instru- 
ment the  wave  length  can  be  found.  In  some  cases  meters  are 
provided  with  a  partially  exhausted  tube  containing  some  gas, 
such  as  helium  or  neon,  to  be  connected  across  the  terminals 
of  the  condenser  to  indicate  resonance.  When  the  meter  is  in 
resonance  there  is  a  maximum  current  flowing  in  its  circuit, 
and  this  produces  a  maximum  voltage  across  the  condenser 
terminals.  This  potential  causes  a  very  small  current  to  flow 
through  the  gas,  which  is  lighted  up  thereby,  and  thus  indicates 
the  setting  for  resonance  from  which  the  wave  length  can  be 
found  as  before.  In  other  cases  it  is  convenient  to  use  a  detec- 
tor to  indicate  resonance,  in  which  case  the  meter  becomes  a 


364 


MILITARY  SIGNAL  CORPS  M.IXU.1L 


receiving  set  with  telephones,  etc.,  as  shown  in  figure  48,  where, 
as  before,  C  and  L  are  the  capacity  and  inductance,  D  the 
detector.  T  the  telephones,  etc.  The  setting  of  the  condenser 
where  the  signals  are  loudest  is  the  resonance  point,  from 
which  the  wave  length  can  be  obtained  as  before.  In  a  few 
cases  a  receiving  circuit  such  as  that  shown  in  figure  49  is  used, 
which  from  the  character  of  the  connection  to  the  detector  is 
sometimes  called  a  unipolar  connection.  The  explanation  of  its 


FIG.    48.—  DETECTOR   USED   TO   INDICATE    RESONANCE 

operation  is  that  when  the  current  circulates  in  the  wave  meter 
itself  there  is  current  enough  sent  along  the  short  wire  to 
operate  the  detector  and  telephones. 

In  addition  to  these  uses  of  the  wave  meter  at  a  transmit- 
ting station  there  are  other  equally  important  ones  at  a  receiv- 
ing station  which  will  be  described  under  the  subject  of 
receivers. 

NATURAL    OR    FUNDAMENTAL    WAVE    LENGTH,    FREQUENCY, 
AND     PERIODS 

One  of  the  simplest  and  at  the  same  time  one  of  the  most 
important  uses  of  a  wave  meter  at  a  transmitting  station  is  in 
the  measurement  of  the  fundamental  wave  length  of  an  an- 
tenna, which  will  be  described  next.  It  has  been  stated  that  a 
circuit  having  a  capacity  C  and  inductance  L  has  a  wave  length 


=  2-jr  v  -\/   LC,    a    frequency    N.  — 


1 


and 


period 


T=  —  r= 


These  values  are  generally  called,  respec- 


tively,  the   natural  or   fundamental  wave   length,  frequency,   and 
period.    These  terms  apply  to  an  antenna  as  well  as  to  a  closed 


RADIO  TELEGRAPH Y 


365 


circuit.  Although  the  antenna  has  no  coil  or  condenser  in  its 
circuit,  the  inductance  is  distributed  along  the  length  of  the 
wire,  as  is  the  capacity.  In  such  a  circuit  it  is  said  that  there 


FIG.  49.— CIRCUIT  WITH  UNIPOLAR  CONNECTION  TO  DETECTOR 

is  distributed  inductance  and  distributed  capacity,  as  distinguished 
from  the  concentrated  or  lumped  inductance  and   lumped  capacity 
in  a  coil  and  condenser  of  a  local  circuit.    Theory  and  experi- 
ment have  shown  that  a  single  vertical  wire  of  length  L  has  a 
natural    wave    length    of    about    4    times    its    length ;    that    is,    the 
fundamental   wave    length    is    approximated   4L.     Thus,    a   wire 
100   feet  long  will  give   a    fundamental   wave   length   of  400   feet; 
that  is,  about  122  meters,  in  even  numbers. 
1  inch  —  2.54  centimeters. 
1  foot  =  30.48  centimeters. 
100  feet  =3,048  centimeters  =  30.48  meters. 
400  feet  =  122  meters. 

If  the  single-wire  antenna  is  of  the  inverted  "L"  type  or  is 
horizontal,  the  fundamental  wave  length  will  be  increased  to 
between  4L  and  5L.  If  there  are  several  wires  in  the  antenna 
these  simple  relations  do  not  apply  and  the  fundamental  wave 
length  must  be  measured  by  a  wave  meter. 

The  plain  Marconi  antenna,  shown  in  figure  34,  is  one  of  the 
simplest  circuits  for  the  measurement  of  the  fundamental  wave 
length  of  an  antenna. 

A  single  turn  of  wire  4  or  5  inches  in  diameter  is  often 
inserted  in  the  antenna  near  the  ground  where  the  potential  is 
low,  which  serves  as  a  convenient  means  of  coupling  the  wave 
meter  to  the  antenna.  The  insertion  of  such  a  small  turn  has 
no  appreciable  effect  on  the  fundamental  wave  length,  and  in 
many  stations  it  forms  a  permanent  part  of  the  antenna. 

The  fundamental  wave  length   of  an   antenna  in  small-sized 
sets,  as  in  field  sets  or  on  artillery  tugs,  may  be  as  short  as 


366 


200  to  250  meters,  and  in  large-sized  sets  may  be  as  long  as 
1,500  to  2,000  meters.  In  general  the  longer  the  antenna  wires, 
the  higher  the  masts,  and  the  greater  the  number  of  the  wires 
the  longer  is  the  fundamental  wave  length. 

In  the  circuits  shown  in  figure  35-42,  illustrating  some  of  the 
common  types  of  transmitting  circuits,  it  will  T>e  noted  that  a 
coil  has  always  been  inserted  in  series  between  the  antenna  and 
ground.  The  insertion  of  such  an  inductance  always  increases 
the  wave  length  of  the  circuit.  Thus  the  fundamental  wave 
length  of  a  certain  antenna  alone  may  be  300  meters ;  an  an- 
tenna coil  of  inductance  of  0.12  millihenry  is  inserted  and  the 
wave  length  of  the  circuit,  antenna-coil-ground,  has  now  been 


u 


FIG.  SO.— SERIES  CONDENSER  IN  CIRCUIT 
TO  SHORTEN  WAVE  LENGTH 

increased  to  about  600  meters.  It  is  evident  then  that  none  of 
the  transmitting  sets  of  figures  35-42  can  radiate  a  wave  length 
shorter  than  the  fundamental  wave  length  of  the  antenna  itself.  In- 
asmuch as  both  ships  and  shore  stations  must  be  prepared  to  use 
a  wave  length  of  300  meters,  according  to  the  regulations  of  the 
International  Radio  Telegraph  Convention,  it  is  evident  that 
the  wave  length  must  be  shortened. 

The  insertion  of  a  series  condenser,  as  shown  in  figure  50, 
always  shortens  the  wave  length  of  the  circuit.  Thus,  if  an 
antenna  installed  on  a  ship  was  found  to  have  a  fundamental 
wave  length  of  450  meters  and  it  became  necessary  to  use  a 


RADIO  TELEGRAPHY 


367 


wave  length  of  300  meters,  a  coil  must  be  inserted  in  the 
antenna  circuit  to  permit  it  to  be  coupled  to  the  closed  circuit, 
which  would  lengthen  the  wave  length  somewhat,  and  then  a 
series  condenser  must  be  inserted  to  bring  the  wave  length  of 
the  circuit  antenna-coil-condenser-ground  to  300  meters.  Such 
a  condenser  should  be  used  only  when  it  is  absolutely  neces- 
sary, as  it  is  generally  subjected  to  high  potentials  which  give 
brush  discharges  and  consequent  losses.  In  many  cases  it  is 
better  to  install  a  second  and  smaller  antenna  having  a  funda- 
mental wave  length  sufficiently  short  for  the  purpose  in  ques- 
tion. This  has  often  been  done  both  on  ships  and  at  shore 
stations.  When  transmitting  on  the  short  antenna,  the  station 
end  of  the  large  antenna  should  be  left  insulated,  and  vice  versa, 
when  transmitting  on  the  large  antenna,  the  short  antenna 
should  be  left  insulated  or  else  connected  into  circuit  as  part 
of  the  large  antenna. 

TUNING  OF  TRANSMITTING  SETS 
MECHANICAL  ILLUSTRATION  OF  COUPLING 

Before  describing  the  methods  of  tuning  the  various  types 
of   transmitters   and   the   measurement    of   the    radiated   wave 


FIG.    51— MECHANICAL   ANALOGY   OF    RADIO   OSCILLATIONS 

lengths,  some  mention  must  be  made  of  coupling  and  its  effects 
on  the  tuning  of  circuits. 

The  theory  of  coupled  circuits,  including  that  of  the 
quenched-spark  transmitter,  can  be  simply  illustrated  by  a 
mechanical  model  consisting:  of  two  equal  weights  suspended 


368 


MILITARY  SIGNAL  CORPS  MAXL'.IL 


by  two  equal  lengths  of  string  from  points  on  a  slightly 
stretched  string,  as  shown  in  figure  51.  If  the  weight  P  is 
pulled  to  one  side  and  released  it  will  execute  a  series  of 
damped  oscillations  (corresponding  to  the  charging  and  the 


FIG.  S2.-GRAPHIC  REPRESENTATION  OF  OSCILLATIONS 

oscillatory  discharging  of  the  primary  or  closed-circuit  con- 
denser). On  account  of  movements  of  the  stretched  string 
(corresponding  to  the  coupling)  this  soon  causes  the  weight  S 
to  begin  oscillating  (corresponding  to  the  induced  oscillations 
in  the  secondary  circuit),  and  in  a  short  time  it  will  be  oscillat- 
ing very  nearly  as  much  as  P  had  been  doing,  but  in  the  mean- 
time P  has  practically  stopped  oscillating.  In  a  short  time, 
however,  P  will  be  oscillating  nearly  as  much  as  before,  but  S 
will  have  stopped.  Thus  it  is  seen  that  the  energy  is  first  in 
one  oscillating  weight  and  then  in  the  other,  or  that  there  is  a 
transfer  of  energy  back  and  forth  from  one  to  the  other.  This 
exchange  will  continue  until  the  energy  is  all  wasted  or  used 
up  in  friction,  etc.  This  can  be  represented  as  in  figure  52, 
where  the  upper  and  lower  curves  correspond  respectively  to 
the  oscillations  of  the  weights  P  and  S.  It  will  be  noted  that 
in  both  curves  of  figure  52  the  amplitudes  do  not  die  down 
steadily  toward  zero,  but  rather  through  a  series  of  values. 
Whenever  such  a  series  of  maximum  and  minimum  values 
occur,  sometimes  called  beats,  it  can  be  shown  by  theory  that  it 
is  due  to  the  fact  that  each  weight  is  oscillating  successively 
at  two  slightly  different  rates  or  frequencies,  one  being  slightly 
slower  and  the  other  slightly  faster  than  its  normal  rate;  that 
is,  when  not  coupled  with  the  other  weight.  In  general,  it  will 
be  found  that  the  less  the  movement  of  the  horizontal  string 
(corresponding  to  loose  coupling)  the  less  frequent  will  be  the 


RADIO  TELEGRAPHY 


369 


transfer  of  energy  from  one  weight  to  the  other,  and,  vice 
versa,  the  greater  the  movement  of  this  string  (corresponding 
to  close  coupling)  the  more  frequent  will  be  the  transfer. 

If  two  circuits,  one  of  which  contains  a  spark  gap,  are  sep- 
arately tuned  to  the  same  frequency  or  wave  length  by  means 
of  a  wave  meter  and  then  are  very  loosely  coupled,  it  will  be 
found  that  there  can  be  detected  only  one  wave  length  in  each, 
which  is  the  same  as  that  to  which  they  were  independently 
adjusted  at  first,  for  example,  as  shown  by  the  curve  with 
the  single  hump  of  300  meters  in  figure  53.  When,  however,  the 
coupling  has  been  somewhat  increased  or  made  tighter  it  will 


200  300 

Wave  Length:— Meters 


400 


FIG.  S3.— WAVE  CURVES  OF  LOOSE  AND  CLOSE  COUPLING 

be  found  that  now  there  are  two  wave  lengths  in  each  circuit, 
one  of  which  is  shorter  and  the  other  longer  than  that  to  which 
the  circuits  were  tuned  at  first.  At  this  coupling  no  readjust- 
ment of  the  tuning  of  the  circuits  can  be  made  which  will  give 
a  single  wave  in  both  of  the  same  length  as  before.  If  the 
coupling  is  still  farther  increased,  the  two  wave  lengths  will  be 
separated  still  farther  from  the  single  value  first  measured. 
If  the  circuit  containing  the  spark  gap  is  the  closed  oscillatory 
or  primary  circuit  of  a  transmitter  and  the  other  circuit  is  the 
open  or  radiating  circuit,  then  it  is  evident  that  two  wave 


370  MILITARY  S1GX.-1L  COKl'S  M.lXt'.lL 

lengths  will  be  radiated  as  shown  in  figure  53,  one  at  a  wave 
length  of  275  meters  and  the  other  at  a  wave  length  of  330 
meters. 

The  two  very  loosely  coupled  circuits  with  the  same  wave 
length  in  each  correspond  to  the  case  of  a  very  small  motion  of 
the  string  with  a  single  transfer  of  energy  from  one  weight  to 
the  other.  The  closely  coupled  circuits  with  two  wave  lengths 
in  each  correspond  to  the  case  of  a  large  motion  of  the  string 
with  frequent  transfers  between  the  two  weights.  In  other 
words  in  very  loosely  coupled  circuits  the  normal  frequency  or 
wave  length  of  each  is  unchanged,  and  only  one  wave  length 
can  be  detected  in  both.  On  the  other  hand,  in  closely  coupled 
circuits  the  normal  frequency  or  wave  length  of  each  is 
changed,  being  made  slower  (longer  wave  length)  and  then 
faster  (shorter  wave  length),  so  that  oscillations  are  taking 
place  successively  at  two  lengths  as  shown  by  the  wave  meter 
in  figure  53.  The  existence  of  the  two  frequencies  is  thus  due 
to  the  transferring  of  the  energy  back  and  forth  between  the 
two  circuits,  the  disadvantages  of  which  will  be  mentioned  in 
the  description  of  quenched  spark  sets. 

TUNING  WITHOUT  WAVE   METER 

The  circuits  of  a  directly  or  inductively  coupled  set  using  the 
ordinary  type  of  open  spark  gap  can  be  tuned  to  resonance, 
either  with  or  without  the  help  of  a  wave  meter,  but  the  meter 
should  be  used  whenever  possible.  If  no  wave  meter  is  avail- 
able the  adjustments  can  be  made  as  follows  :  Insert  several 
turns  of  inductance  in  the  open  or  antenna  circuit,  a  few  in  the 
closed  circuit,  and  note  the  antenna  ammeter  reading.  Change 
the  number  of  turns  in  the  closed  circuit  and  also  the  coupling 
if  necessary  until  a  maximum  reading  is  obtained  in  the  am- 
meter. Make  a  record  of  these  best  adjustments — the  number 
of  turns  in  each  circuit,  coupling,  and  antenna  ammeter  reading. 
Next,  using  a  different  number  of  turns  in  the  open  circuit, 
repeat  until  the  best  adjustment  is  obtained  under  these  condi- 
tions, and  make  a  record  of  these  readings,  etc.  Sometimes  it 
may  be  more  convenient  to  insert  several  turns  of  inductance 
in  the  closed  circuit  and  then  to  vary  the  number  in  the  open 
circuit  and  the  coupling  between  the  two  circuits  until  a  maxi- 
mum reading  is  obtained  in  the  ammeter.  After  making  a 
record  of  these  best  adjustments,  use  a  different  number  of 
turns  in  the  closed  circuit,  and  adjust  the  number  of  secondary 
turns  and  coupling,  etc.,  as  before.  In  the  first  case  the  closed 
circuit  is  tuned  to  the  open  circuit,  and  in  the  second  case  the 
open  to  the  closed.  Both  methods  are  correct  under  circum- 
stances and  will  give  the  same  adjustments. 


RADIO  TELEGRAPHY  371 

If  there  is  no  ammeter  in  the  antenna  circuit  a  spark  gap 
can  be  connected  in  parallel  with  the  inductance  coil  in  the 
antenna;  that  is,  between  the  antenna  and  ground  and  the 
circuits  adjusted  until  the  longest  spark  possible  is  obtained, 
in  which  case  the  circuits  are  in  resonance  as  before.  The 
ammeter  indicates  when  the  current  in  the  antenna  is  a  maxi- 
mum and  the  gap  when  the  potential  at  the  antenna  is  a  maxi- 
mum, both  of  which  are  conditions  of  resonance.  These  are  the 
simplest  methods,  but  not  the  best.  The  adjustments  should  be 
made  with  a  wave  meter  for  reasons  that  will  be  made  clear  in  the 
following  paragraphs. 

TUNING   WITH    WAVE   METER 

When  a  wave  meter  is  available  the  wave  lengths  of  the 
closed  circuit,  uncoupled  from  the  open  circuit,  should  be  meas- 
ured for  different  numbers  of  turns  in  the  closed  circuit  or 
primary  coil  and  the  results  plotted  as  shown  in  figure  54. 
Next,  using  the  antenna  and  the  open  circuit  inductance  coil 
as  a  plain  Marconi  antenna  similar  to  that  shown  in  figure  34, 
the  wave  lengths  for  different  numbers  of  turns  should  be 
measured  and  the  results  plotted  as  shown  in  the  figure.  It 
will  be  seen  that  when  4  turns  are  in  the  primary  circuit  and 
9  in  the  open,  both  are  tuned  to  a  wave  length  of  600  meters. 
If  these  turns  were  used  in  a  directly  connected  or  coupled  set 
with  a  single  coil,  as  shown  in  figure  37,  and  the  coupling,  etc., 
adjusted  to  give  a  maximum  antenna  ammeter  reading  as  de- 
scribed in  the  previous  paragraph,  it  will  almost  certainly  be 
found  that  when  the  radiated  wave  length  is  tested  with  a  wave 
meter,  loosely  coupled  with  a  single  turn  in  the  antenna  or 
ground  circuit,  there  will  be  two  wave  lengths  or  two  humps, 
as  they  are  often  called,  such  as  are  shown  in  figure  53.  These 
two  wave  lengths  are  caused  by  too  close  coupling  between 
the  circuits.  They  can  not  be  shown  by  the  antenna  ammeter, 
which  gives  the  sum  of  the  currents  flowing  in  the  circuit  with- 
out regard  to  the  wave  lengths,  but  will  always  be  shown  by  a 
wave  meter,  which  gives  the  strengths  of  the  currents  at  the 
different  wave  lengths.  In  many  cases  it  will  be  found  that 
when  the  coupling  is  loosened  and  the  circuits  slightly  retuned 
the  antenna  ammeter  reading  may  be  reduced,  bat  the  wave 
meter  reading  will  show  only  a  single  wave  length  or  hump 
and  the  current  at  that  value  will  be  much  larger  than  with  the 
previous  adjustment.  As  the  wave  meter  circuit  corresponds 
very  closely  to  the  receiving  circuit  at  the  distant  station,  it  will 
almost  certainly  be  found  that  the  adjustment  to  a  single  wave 
length  will  give  louder  signals  than  the  other  adjustment. 


372 


MILITARY  SIGNAL  CORPS  MANUAL 


Thus  in  figure  53  are  shown  two  curves  taken  from  an  actual 
transmitter,  the  one  with  the  double  hump  when  the  circuits 
were  tuned  to  a  maximum  antenna  reading  and  the  other  when 
the  circuits  were  more  loosely  coupled  and  adjusted  to  a  single 
wave  length  with  a  wave  meter.  The  antenna  ammeter  reading 
was  less  in  the  second  case  than  in  the  first,  but  the  wave  meter 
test  and  a  receiving  test  at  the  other  station  showed  that  much 
was  gained  both  in  loudness  of  signals  and  in  sharpness  of  tun- 
ing. Although  in  some  cases  it  may  be  possible  to  radiate  more 
energy  with  the  double  wave  lengths,  yet  not  always  will  the 


Turns 


8  10  12  14  16  If 


FIG.   54.— CURVES  OF   OPEN   AND  CLOSED   CIRCUIT   WAVE   LENGTHS 
MEASURED    WITH    WAVE    METER 


signals  be  louder,  for  the  reason  that  most  receiving  sets  can 
be  adjusted  to  receive  only  one  wave  length  at  any  one  adjust- 
ment and  all  energy  at  other  wave  lengths  or  in  other  humps 
is  wasted  as  far  as  this  receiver  is  concerned.  In  a  very  few 
cases  receivers  have  been  designed  to  receive  at  two  wave 
lengths  or  humps  at  the  same  time,  in  which  case  the  second 
wave  length  will  not  be  wasted;  but  such  receivers  have  the 
disadvantage  of  being  subject  to  interference  on  both  wave 
lengths. 

There  is  a  most  serious  objection  to  the  use  of  transmitters 
with  double  wave  lengths,  or  humps,  on  account  of  the  inter- 
ference which  they  cause.  Thus  in  figure  53  it  is  seen  that  this 


RAD1OTELEGRAPHY  373 

transmitter  is  sending  out  signals  on  275  and  330  meters  wave 
lengths  and  is  preventing  another  station  from  working  on 
either  wave  length,  whereas  if  properly  tuned  as  at  300  meters 
the  interference  is  reduced  to  one  wave  length.  It  is  for  this 
reason  that  legislation  has  been  enacted  prohibiting  the  opera- 
tion of  a  station  with  two  such  humps.  The  law  permits  the 
use  of  the  double  hump  when  one  is  not  greater  than  one-tenth 
of  the  other  as  tested  in  a  wave  meter.  There  are  further 
restrictions  about  the  larger  of  the  two  humps,  or  about  a 
single  hump  in  case  only  one  is  found.  It  must  not  be  broad 
or  flat  topped,  meaning  that  the  oscillations  in  the  antenna  can 
not  be  highly  damped,  as  is  the  case  of  the  plain  Marconi 
antenna  of  figure  34.  A  measure  of  the  damping  is  prescribed 
which  must  not  be  exceeded.  This  measure  is  called  the 
logarithmic  decrement. 


THEORY  OF  OPERATION   OF  QUENCHED-GAP  TRANSMITTER 

Most  of  the  sets  now  supplied  by  the  Signal  Corps  are  of  the 
quenched-gap  type,  and  a  brief  outline  of  the  theory  of  its 
operation  will  be  given. 

If  in  a  quenched-spark  transmitter,  with  its  circuits  correctly 
adjusted  to  radiate  a  single  sharply  defined  wave  length,  the 
gap  is  replaced  by  an  ordinary  type  of  open  gap,  it  will  be 
found  by  a  wave  meter  test  that  there  are  now  two  wave 
lengths.  This  shows  that  the  single  wave  length  was  not 
secured  by  an  adjustment  of  a  very  loose  coupling  between  the 
circuits,  but  rather  by  a  property  of  the  quenched  gap  itself. 
An  explanation  of  the  action  of  the  gap  can  be  made  by  refer- 
ence to  figure  52,  where  it  will  be  noted  that  near  the  point 
marked  "Q"  in  the  upper  curve,  the  amplitude  of  the  primary 
current  has  reached  its  first  minimum  value  in  the  course  of 
the  beats.  On  account  of  the  strong  cooling  action  of  the  gap, 
due  to  the  use  of  the  cooling  flanges  and  the  blower,  the  spark 
is  quenched  or  stopped  at  this  point  in  the  wave  train  and  the 
primary  circuit  is  thus  opened.  When  proper  cooling  is  pro- 
vided the  spark  can  not  be  started  again  in  this  wave  train  and 
the  gap  is  not  broken  down  until  the  next  alternation.  At  the 
same  time  that  the  primary  current  is  a  minimum  it  will  be 
noted  that  the  secondary  current  is  a  maximum;  that  is,  practi- 
cally all  the  energy  is  located  in  the  secondary  circuit.  As  the 
primary  circuit  has  now  been  opened  so  there  can  be  no  trans- 
fer of  energy  back  to  it,  all  is  retained  in  the  secondary,  where 
it  is  available  for  radiation.  As  a  result  there  are  no  beats  in 
the  secondary,  the  oscillations  in  it  persist  for  a  longer  time, 


374  MILITARY  SIGXAL  CORPS  MANUAL 

and  more  energy  is  radiated.  This  is  shown  in  figure  55,  where 
the  primary  current  has  been  stopped  at  the  point  correspond- 
ing to  Q  of  figure  52  and  the  secondary  continues  to  oscillate 
as  shown.  Whenever  there  is  a  transfer  of  energy  back  to  the 
primary  where  it  is  not  available  for  radiation  there  are  losses 
due  to  heating,  etc.,  and  so  less  energy  is  left  for  radiation  than 
if  there  had  been  no  such  transfer.  The  quenched  spark  trans- 
mitter has  then  two  advantages  over  a  transmitter  with  the 
ordinary  type  of  open  gap — greater  efficiency  and  the  radiation 
of  more  sharply  defined  wave  lengths. 

When  the  adjustments  of  a  quenched  spark  transmitter  have 
been  correctly  made — that  is,  the  circuits  are  in  resonance,  the 


FIG.    55.— OSCILLATIONS    OF    PRIMARY    AND    SECONDARY    CURRENT 
WITH  QUENCHED  SPARK  TRANSMITTER 

coupling  is  right,  etc. — a  simple  experiment  will  show  that  the 
primary  current  is  a  minimum ;  that  is,  the  spark  has  been 
quenched  and  the  primary  current  has  been  stopped  quickly,  as 
at  the  point  Q  of  figure  52,  and  that  at  the  same  time  the 
secondary  current  is  a  maximum ;  that  is,  it  persists  for  a  long 
time,  as  shown  in  figure  55.  The  experiment  consists  in  making 
simultaneous  readings  of  the  currents  in  the  primary  and  sec- 
ondary oscillating  circuits,  and  plotting  the  readings  for  the 
different  couplings  of  the  primary  and  secondary  circuits.  This 
is  shown  in  figure  56,  where  the  scale  at  left  is  in  amperes  and  that 
at  the  bottom  is  the  coupling  of  the  two  circuits,  the  upper  curve 
being  for  the  primary  and  the  lower  for  the  secondary.  At  the 
point  of  correct  coupling  the  primary  current  was  a  minimum  and 
the  secondary  or  antenna  current  a  maximum. 

From  these  curves  it  will  be  seen  that  the  coupling  of  the  two 
circuits  of  a  quenched-spark  transmitter   is   a  very  important  and 


RADIOTELEGRAPH  Y 


375 


critical  adjustment,  upon  the  correct  value  of  which  the  efficiency 
is  largely  dependent. 

Sometimes  when  the  adjustments  of  a  quenched-spark  set 
are  not  correct  it  is  possible  to  detect  two  wave  lengths,  but 
of  very  small  amplitude,  in  addition  to  the  single  wave  length 
just  mentioned,  one  of  these  being  of  shorter  and  the  other 
of  longer  wave  length  than  the  normal.  The  development  of 
these  two  wave  lengths  is  generally  due  to  excessive  coupling 
so  that  the  spark  is  not  quenched  at  the  proper  point  but -allows 
one  or  two  transfers  of  the  secondary  energy  back  into  the 
primary  during  which  two  wave  lengths  are  produced.  After 


Coupling 

FIG.   56.— CURVES   OF   PRIMARY    AND   SECONDARY 
OSCILLATING  CIRCUITS 

the  spark  is  properly  quenched,  the  energy  is  retained  in  the 
secondary,  and  the  normal  wave  length  of  much  greater  ampli- 
tude is  developed. 


ARRANGEMENTS  AT  THE  RECEIVING   STATION 

The  electromagnetic  waves  sweeping  across  the  antenna  at 
the  receiving  station  generate  damped  alternating  currents 
therein  of  the  same  frequency  as  those  in  the  transmitting  antenna.  At 
great  distances  the  oscillations  or  currents  are  exceedingly  feeble, 
perhaps  only  a  few  millionths  of  an  ampere,  and  it  requires  cor- 
rectly adjusted  circuits  and  very  sensitive  devices  to  detect  them. 
The  various  types  of  receiving  circuits  will  be  described  next,  and 
the  detectors  later. 

It  is  evident  that  the  strongest  oscillations  will  be  produced  in 
the  receiving  antenna  when  it  has  the  same  frequency  or  wave 
length  as  the  transmitting  antenna.  In  the  simplest  case  an  antenna 


376 


MILITARY  SIGNAL  CORPS  MANUAL 


identical  in  construction  with  that  at  the  transmitting  station  can  be 
used,  in  which  the  detector  is  inserted  directly  by  the  antenna,  as 
shown  in  figure  57.  This  circuit  is  sometimes  known  as  the  plain 
Marconi  antenna  for  receiving  and  corresponds  to  the  transmitting 


FIG.    57.— PLAIN    MARCONI    RE- 
CEIVING  ANTENNA   CIRCUIT 


FIG.    58.— TUNED   RECEIVING 
CIRCUIT 


circuit  of  figure  34.  Owing  to  its  many  disadvantages,  such  as 
trouble  from  static,  interference,  etc.,  this  circuit,  like  the  plain 
transmitting  circuit,  is  not  now  used  in  practical  radiotelegraphy. 


A  simple  circuit  for  tuning  the  receiving  antenna  to  the  same 
frequency  or  wave  length  as  the  transmitter  is  shown  in  figure  58, 
where  the  adjustments  are  made  by  using  a  variable  inductance; 
thus  the  larger  the  number  of  turns  in  circuit  the  greater  the  in- 
ductance and  the  lower  the  frequency  or  the  longer  the  wave  length 
of  the  oscillations  to  which  it  is  tuned,  and,  vice  versa,  the  fewer 
the  number  of  turns  the  less  the  inductance  and  the  higher  the 
frequency  or  the  shorter  the  wave  length  of  the  oscillations.  In 
this  case  the  detector  D  is  in  a  branch  circuit  with  the  condenser  S 
and  the  telephones  T,  which  is  connected  across  a  variable  number 
of  turns  by  means  of  a  sliding  contact.  It  is  seen  that  the  detector 
circuit  is  thus  connected  directly  to  the  antenna  inductance  coil  and 
hence  is  called  a  directly  connected  or  directly  coupled  receiving 


RADIO  TELEGRAPHY 


377 


set,  thus  corresponding  to  the  directly  connected  transmitting  sets 
of  figures  36,  37  and  38.  This  circuit  is  of  a  type  si  nilar  to  that 
in  the  double-slide  tuning  coil  sets  formerly  used  by  the  Signal 


FIG.   59.-RECEIVIXG   CIRCUIT  WITH 
SERIES    CONDENSER 


Corps.  In  order  to  be  able  to  tune  the  antenna  circuit  to  wave 
lengths  shorter  than  the  fundamental,  as  is  often  necessary,  a  series 
condenser  must  be  used,  as  shown  in  figure  59. 

INDUCTIVELY     CONNECTED     CIRCUITS 

Most  receiving  sets  now  in  use  are  of  the  inductively  con- 
nected or  inductively  coupled  type,  as  shown  in  figures  60  and  61, 
in  which  it  is  seen  that  the  oscillations  in  the  tuned  antenna  circuit 
induce  oscillations  in  a  circuit  coupled  with  it,  thus  corresponding  to 
the  inductively  coupled  transmitting  sets  of  figures  35  and  39.  In 
this  case  the  antenna  circuit  is  the  primary  and  its  coil  Li  is  generally 
called  the  primary  coil  of  the  receiving  transformer.  The  closed 
circuit  is  the  secondary  circuit  and  its  coil  La  is  the  secondary  of  the 
receiving  transformer.  It  is  to  be  noted  that  these  terms  are  the 
reverse  of  those  used  in  the  transmitting  circuit.  Circuits  of  the  in- 
ductively connected  type  have  advantages  over  those  of  the  di- 
rectly connected  type,  in  that  they  can  generally  be  rendered  less 
liable  to  static  disturbances  and  will  have  sharper  tuning,  so  that  it 
is  more  nearly  possible  to  cut  out  undesired  stations,  etc. 


378 


MILITARY  SIGXAL  CORPS  MAX  UAL 


The  closed  or  secondary  circuits  arc  of  two  general  types 
called  untuned  and  tuned,  as  shown  respectively  in  figures  60  and  61. 

In  the  untuned  circuit  there  is  no  secondary  tuning  con- 
denser, the  only  adjustment  being  in  the  number  of  turns  in 
Lz,  which  is  generally  in  steps  of  many  turns.  In  the  adjustment 
of  such  a  set  to  get  signals  of  maximum  loudness,  the  circuits 
must  be  adjusted  to  resonance,  and  the  proper  coupling  between 
them  be  used.  The  primary  circuit  will  be  sharply  tuned,  but 
the  secondary  only  very  broadly  if  tuned  at  all.  If  a  close  coup- 
ling is  used  between  the  circuits  the  tuning  of  both  will  be  broad, 
and  hence  the  set  will  have  the  disadvantage  of  being  liable  to 
severe  interference.  Under  certain  conditions,  however,  as  in 
searching  for  an  unknown  station,  it  may  be  of  advantage  to  use 
this  coupling  at  first,  and  then  when  the  station  has  been  picked  up, 


FIG.  60.— UNTUNED  INDUCTIVE- 
LY  COUPLED    RECEIVING 
CIRCUIT 


FIG.    61.— TUNED    INDUCTIVELY 

COUPLED    RECEIVING 

CIRCUIT 


to  loosen  the  coupling  and  to  make  such  changes  in  both  circuits  as 
will  give  the  sharpest  tuning  and  the  loudest  signals.  In  many  re- 
ceiver sets  of  this  type  the  so-called  untuned  secondary  circuit 
is  really  a  broadly  tuned  one  in  which  the  inductance  of  the  coil 
and  its  distributed  capacity  form  the  tuning  elements.  The  range 
of  wave  lengths  to  which  each  step  is  thus  broadly  tuned  is  gen- 
erally marked  for  each  contact,  thus  400  to  600  meters,  600  to  1,000 
meters,  etc. 

In  the  tuned  circuit  there  is  a  variable  tuning  condenser,  as  O 
in  figure  61,  the  adjustment  of  which  is  necessary  to  secure  the 
maximum  loudness  of  signals.  The  secondary  inductance  is  some- 
times variable  by  steps  and  in  a  few  cases  by  single  turns.  It  must 


RADIOTELEGRAPHY  379 

be  noted  that  adjustments  for  any  wave  lengths  can  be  made  with 
different  combinations  of  inductance  and  capacity.  In  general  it  will 
be  found  that  in  both  the  primary  and  secondary  circuits  there 
is  a  best  value  of  these  combinations  of  inductance  and  capacity 
for  any  given  transmitting  station,  and  that  these  combinations 
may  be  different  for  each  different  station,  and  hence  must  be 
found  by  trial.  The  tuning  of  the  inductively  coupled  receiving 
set  requires  a  careful  adjustment  of  both  circuits  and  of  the 
coupling  between  them.  The  three  adjustments  are  all 
dependent  one  on  the  other,  so  that  if  the  circuits  are  adjusted 
to  resonance  with  loose  coupling  and  the  coupling  is  then 
increased  and  made  close,  the  circuits  will  be  put  out  of  reson- 
ance and  retuning  of  both  is  necessary.  Similarly,  if  the  cir- 
cuits are  closely  coupled  and  then  each  is  tuned,  it  may  be 
found  that  there  are  two  points  of  resonance  or  two  wave 
lengths  in  each  circuit,  although  only  a  single  wave  length  is 
being  radiated  by  the  transmitting  station.  On  account  of 
these  changes  in  wave  length  with  changes  in  coupling,  it  is 
best  to  work  with  as  loose  a  coupling  as  possible  in  this  type 
of  receiver,  also  the  tuning  will  be  sharper  and  the  interference 
will  be  less  under  these  conditions.  There  is  an  additional 
advantage  in  some  cases,  as  the  secondary  circuit  can  be  cali- 
brated in  wave  lengths  for  different  settings  of  the  condenser, 
and  hence  the  wave  lengths  of  the  received  signals  measured 
at  the  time  of  reception.  The  best  value  of  the  coupling  will 
depend  not  only  on  the  constants  of  the  circuits,  but  also  upon 
the  character  of  the  waves  radiated  by  the  transmitter.  The 
broader  the  tuning  in  the  transmitting  station  or  the  larger 
the  damping  of  the  waves  radiated  by  it,  the  closer  may  be 
the  coupling  between  the  circuits  and  vice  versa :  the  sharper 
the  tuning  in  the  transmitting  station, .or  the  smaller  the  damp- 
ing of  the  radiated  waves,  the  looser  must  be  the  coupling 
between  the  circuits.  In  some  cases  in  actual  practice  it  is 
found  that  when  sustained  or  undamped  waves  are  used,  the 
damping  of  which  is  zero,  the  coupling  between  the  circuits 
must  be  made  so  loose  that  signals  of  the  same  wave  length  from 
a  station  using  highly  damped  waves  may  riot  be  heard  at  all. 

STATIC    AND    INTERFERENCE 

The  elimination  of  static  disturbances  and  interference  from 
other  stations  is  one  of  the  most  difficult  problems  in  radioteleg- 
raphy.  At  the  present  time  it  is  doubtful  if  there  is  a  complete 
solution  of  both  troubles.  The  elimination  of  static  is  dependent 
largely  on  the  design  of  the  apparatus  at  the  receiving  station, 
whereas  that  of  interference  is  dependent  on  both  the  transmit- 


3X0 


MILITARY  SIGNAL  CORPS  MANUAL 


ting  and  the  receiving  apparatus.  In  some  cases  static  can  be  cut 
down  by  connecting  a  very  high  resistance,  as  10,000  ohms  or  more, 
between  the  antenna  and  ground,  thus  giving  a  shunt  path  to  earth 
for  the  static.  In  many  cases  a  very  loose  coupling  between  the 
receiver  circuits  may  reduce  the  static  more  than  the  desired  signals, 
which  although  much  weakened  can  still  be  read.  When  the  trans- 
mitted signals  are  of  high  pitch  they  can  be  read  through  moderate 
static  much  easier  than  those  of  low  pitch.  If  the  diaphragms  of 
the  receiving  telephones  are  tuned  to  the  pitch  of  the  transmitted 
signals  the  static  can  be  still  further  eliminated.  There  are  many 
types  of  circuits  which  have  been  suggested  as  useful  in  reducing 
static,  which  although  effective  in  stations  with  small  antennae  are 
often  of  little  use  with  the  large  antennae  which  must  be  used  in 
powerful  transmitting  stations.  This  fact  has  sometimes  led  to 
the  installation  of  two  antennae  at  a  station,  a  large  one  only  for 
transmitting  and  a  small  one  of  two  or  three  wires  for  receiving. 
It  is  often  possible  then  to  get  messages  on  the  small  antenna  that 
can  not  be  copied  on  the  large  one. 

The  elimination  of  interference  is  dependent  on  both  the  trans- 
mitter and  receiver  design.     The  more  nearly  that  the  transmitting 


Wave  Length 

FIG.    62.— TRANSMITTER    CURVES 
FOR  RESONANCE  TUNING 


Ware  Length 

FIG.    63.— RECEIVER    CURVES 
FOR  RESONANCE  TUNING 


oscillations  are  undamped ;  that  is,  the  more  sharply  that  the  radiated 
energy  is  confined  to  single  wave  lengths ;  and  at  the  same  time  the 
lower  the  resistance  of  the  receiver  circuits  and  the  more  sensitive 
the  detector,  the  more  certainly  is  it  possible  to  prevent  interference. 
Thus  if  two  stations  have  transmitters  whose  radiated  wave  lengths, 
as  tested  by  a  wave  meter,  are  as  shown  by  a  in  figure  62,  and  have 
receivers  whose  circuits  permit  of  reception  of  wave  lengths  as 
shown  by  a  in  figure  63,  it  is  evident  that  they  can  work  together 
without  causing  interference  at  other  stations  and  without  beinsr 
subject  to  interference  except  at  lengths  very  near  their  own.  On 
the  other  hand,  if  two  stations  radiate  waves  as  shown  by  b  in 
figure  62,  and  receive  w,ave  lengths  as  shown  by  b  in  figure  63,  it  is 
evident  that  they  will  cause  interference  at  other  stations  on  account 


RADIO  TELEGRAPHY 


381 


of  the  broad  tuning  of  the  transmitters  and  will  be  subject  to  inter- 
ference on  account  of  the  broad  tuning  of  the  receiving  circuits. 

There  are  many  types  of  circuits  which  have  been  found  useful 
in  helping  to  prevent  interference,  one  of  the  simplest  of  which  is 
the  loosely  coupled  inductive  receiving  set  as  shown  in  figure  61. 
When  these  circuits  are  of  low  resistance,  the  inductance  and  capa- 
city of  each  circuit  variable  so  as  to  secure  the  best  combination 
of  the  two,  and  the  coupling  as  loose  as  the  signals  permit,  such  a 
set  can  be  used  to  receive  signals  at  any  one  wave  length  from 
one  station  and  to  exclude  signals  of  slightly  different  wave  lengths 
from  other  stations.  This  property  of  the  reception  of  signals  of 
one  wave  length  and  the  exclusion  of  those  of  other  wave  lengths  is 
called  selectivity  and  such  a  receiver  is  said  to  be  selective.  In  figure 


FIG.  64.-AN  INTERFERENCE  MINIMIZER  CIRCUIT 

64  is  shown  a  receiving  set  which  is  provided  with  an  additional  cir- 
cuit of  coil  L/i  and  Condenser  C7i  connected  between  the  antenna  and 
the    ground,  which    with    the    antenna  is  tuned  to  the  wave  length 
of  the  interfering  station  and   thus   furnishes  a  tuned  sHunt  path 
to  ground  for  the  undesired  signals.     This  is  sometimes  called  an 
interference   minimiser  circuit.     The   connection  of   this  circuit  to 
the  antenna  will  slightly  change  the  tuning  of  the  primary  circuit, 
so   that   both   have   to   be   adjusted   together,   one    to    decrease    the 
undesired    signals    to    a   minimum    and    the    other    to    increase    the 
desired  signals  to  a  maximum.     In  order  to  prevent  the  grounding 
of  the  desired  wave  lengths  by   the   shunt  circuit  at  times  when   it 
is  not  needed,  the  circuit  should  be  opened  by  the  switch.     Figure 

65  is  a   similar   type   of   circuit   for   absorption    of   undesired   wave 
lengths,  the  circuit  being  coupled  to  the  antenna  circuit  as  needed 
and  tuned  to  the  interference, 


382 


MILITARY  SIGNAL  CORPS  MANUAL 


DETECTORS 

The  form  of  detector  first  used  in  radiotelegraphy  was  the 
coherer,  which  permitted  the  signals  to  be  received  on  a  relay  and 
sounder.  The  coherer  is  not  now  used  in  practical  work,  having 
been  replaced  by  other  more  sensitive  and  satisfactory  types  of 
detectors. 

An  important  improvement  in  sensibility  and  certainty  of  opera- 
tion was  made  by  the  introduction  of  the  telephone  receiver  as  the 
receiving  instrument  instead  of  the  sounder,  the  dots  and  dashes 
being  received  as  short  and  long  buzzing  sounds  of  the  same  audible 
frequency  or  note  as  that  at  the  transmitting  station.  Experiments 
have  shown  that  the  ear  is  more  sensitive  to  notes  of  a  high  pitch, 
as  several  hundred  or  a  thousand  vibrations  per  second,  the  latter 
being  given  by  a  500-cycle  alternator,  than  to  notes  of  a  low  pitch, 
as  120  vibrations  per  second,  as  given  by  a  60-cycle  alternator.  It 
has  also  been  found  easier  to  read  a  note. of  high  pitch  than  one 


FIG.   65.— A   CIRCUIT    FOR   ABSORBING    UNDESIRED    WAVE   LENGTHS 

of  low  pitch  in  static  or  other  irregular  disturbances.  These  are 
two  advantages  of  the  high-spark  frequency  or  high-wave  train 
frequency  at  the  receiving  station,  the  corresponding  advantages 
at  the  transmitting  station  having  already  been  mentioned. 

The   high-frequency  currents   in   the    receiving  antenna  have   a 
frequency  of  from,  say,  50,000  to  over  1,000.000  per  second,  but  as 


RADIOTELEGRAPHY 


383 


the  telephone  diaphragm  can  not  vibrate  at  this  great  frequency, 
the  telephone  receiver  can  not  be  used  directly  as  a  radio  receiver. 
Even  if  the  diaphragm  could  vibrate  at  this  frequency,  we  would 
be  unable  to  detect  any  sounds,  as  the  human  ear  does  not  respond 
tf  more  than  about  20,000  vibrations  per  second.  It  is  evident,  then, 
that  the  telephone  receiver  itself  can  not  make  the  signals  audible, 
but  that  it  must  be  used  in  connection  with  some  of  the  detectors 
described  below. 

A  number  of  forms  of  detectors  have  been  invented,  most  of 
which  rectify  the  high-frequency  currents — that  is,  change  them 
from  alternating  to  direct  currents  by  some  kind  of  valve  action — 
and  thus  render  them  capable  of  operating  the  telephone  at  an 
audible  frequency.  In  figure  66  the  upper  curve  shows  several 
damped  wave  trains  as  in  the  receiving  circuits,  the  middle  curve 
shows  them  as  theoretically  rectified  by  the  detector  so  that  the 
current  is  allowed  to  pass  in  one  direction,  and  the  lower  curve  the 
actual  current  through  the  telephone,  where  the  rectified  current  is 
smoothed  out  by  the  inductance  of  the  telephone.  Each  wave  train 
is  practically  the  equivalent  of  a  direct  current  lasting  a  small  frac- 
tion of  a  second,  or  a  pulsating  current,  as  it  is  often  called.  Thus, 


LAA 


A 


AA 


A 


AA 


A 


FIG.    66.— DAMPED    WAVE    TRAINS    RECTIFIED    BY    DETECTOR 
AND  TELEPHONE 

in  the  case  of  a  spark  frequency  of  1,000  per  second  there  will  be 
1,000  pulsations  of  current  as  in  the  lower  curve  of  figure  66,  and 
the  telephone  will  be  operated  as  though  by  a  direct  current  inter- 
rupted 1,000  times  per  second. 

One  of  the  earliest  of  the  rectifying  detectors  that  was  used 
with  a  telephone  was  the  electrolytic,  but  like  the  coherer  it  is  not 
now  used  in  practical  work. 

Other  kinds  of  detectors,  sometimes  called  crystal  or  contact 
detectors,  consist  of  various  substances  in  light  contact,  such  as 
steel-carborundum,  steel-silicon,  etc.;  metallic  contact  on  pyrite, 
galena,  etc. ;  zincite-chalcopyrite,  silicon-arsenic,  silicon-antimony. 


384 


MILITARY  SIGNAL  CORPS  MANUAL 


etc.  These  have  all  been  patented,  and  some  of  them  have  received 
trade  names,  such  as  "perikon"  for  zincite-chalcopyrite,  "pyron"  for 
metallic  contact  on  pyrite,  etc.  In  the  case  of  the  perikon,  silicon- 
arsenic,  silicon-antimony,  etc.,  the  materials  are  embedded  in  flat 
buttons  of  fusible  alloy  or  solder  on  an  adjustable  holder  and  held 
in  light  contact  by  a  spring;  in  the  steel-silicon,  pyrite,  galena,  etc., 
contact  is  made  by  a  light  spring  on  a  universal  jointed  holder. 

Most  of  these  detectors  are  sensitive  to  the  high-frequency  oscil- 
lations without  the  application  of  an  external  electromotive  force, 
as  the  steel-silicon,  galena,  etc.,  and  the  simplest  circuit  in  this  case 
is  shown  in  figure  67,  where  D  is  the  detector,  T  the  telephones,  and 
S  a  fixed  condenser  of  about  0.003-micro farad  capacity.  Other  de- 
tectors are  more  sensitive  when  a  small  electromotive  force,  as 
from  a  potentiometer,  is  applied  to  them  as  the  perikon,  pyron,  etc., 
and  in  this  case  the  circuit  is  shown  in  figure  68,  where  D  is 


FIG.   67.— SIMPLE   DETECTOR 
CIRCUIT 


FIG.    68.— DETECTOR    CIRCUIT 
WITH    POTENTIOMETER 


the  detector,  T  the  telephones,  S  the  condenser,  generally  fixed,  but 
sometimes  variable  by  steps. 

Another  type  of  detector  is  the  vacuum  valve,  or  tube,  of  two  or 
three  elements;  the  latter  called  the  "audion"  and  shown  in  figure 
69,  consists  essentially  of  a  partially  exhausted  bulb  in  which 
have  been  sealed  a  metallic  filament,  F,  two  small  grids,  G,  one 
on  each  side  of  the  filament,  and  two  small  plates  P,  outside  of 
each  grid,  the  plates  and  grids  being  insulated  from  each  other 
and  the  filament.  The  filament  is  heated  to  incandescence  by  a 
storage  battery,  A,  often  called  the  "A  battery,"  of  about  6  volts,  the 
current  from  which  is  regulated  by  means  of  a  small  rheostat,  R. 
The  plates,  P,  entirely  insulated  within  the  bulb,  are  connected  to 
one  terminal  of  the  telephones,  T,  the  other  one  of  which  is  con- 
nected to  a  battery  of  small  dry  cells,  B,  often  called  the  "B  bat- 
t.ry,"  of  30  to  50  volts,  the  number  of  which  in  circuit,  and  hence 
the  voltage,  is  controlled  by  a  switch.  The  positive  terminal  of 


RADIO  TELEGRAPHY 


385 


the  B  battery  should  always  be  connected  to  the  plates,  P,  through 
the  telephones.  The  terminals  of  the  detector  circuit  are  connected, 
one  to  the  base  of  the  filament  and  the  other  to  the  insulated  wire 
grids,  G,  through  a  small  stopping  condenser,  S.  The  action  of  the 
vacuum  valve  seems  to  be  that  of  a  relay,  and  its  operation  is  as 
follows :  Under  the  influence  of  the  hot  filament  the  molecules  of 
gas  remaining  in  the  bulb  acquire  the  property  of  conducting  a 
small  current  on  the  application  of  30  to  50  volts  in  the  direction  of 
filament  to  plates,  but  not  in  the  reverse  direction,  and  if  the 
telephone  is  connected  in  this  circuit  as  shown,  a  small  steady  cur- 
rent will  flow  through  it.  On  the  arrival  of  the  high-frequencv 
oscillations  at  the  grids  and  the  filament  it  is  probable  that  they 
can  flow  only  in  one  direction,  and  during  their  passage  over  part 


FIG.    69.-COXNECTIONS   TO   VACUUM    VALVE    DETECTOR 

of  the  path  of  the  telephone  current  they  change  its  resistance,  and 
hence  the  current  in  the  telephones,  and  thus  make  audible  sig- 
nals. For  reasons  previously  given,  the  pitch  of  the  note  in  the 
telephones  is  the  same  as  that  of  the  spark  frequency  at  the 
transmitting  station. 

A  sensitive  detector  of  a  somewhat  novel  type  is  now  coming 
into  use,  called  the  ticker,  consisting  essentially  of  fine  steel  or 
other  wire  resting  with  light  contact  in  a  groove  on  a  rotating  disk 
of  brass  or  other  suitable  material.  This  detector  can  be  used 
instead  of  D  in  the  circuit  shown  in  figure  67  in  which  the  con- 
denser S  should  now  be  about  0.01  mf.  and  the  telephones  of  low 
resistance. 


386  MILITARY  SIGNAL  CORPS  MANUAL 

TELEPHONES 


The  telephone  receivers  used  in  detector  circuits  are  wound  to 
a  high  resistance,  as  1.000  ohms  or  more  for  each  one  of  a  pair. 
The  reason  for  this  is  as  follows:  The  movements  of  the  tele- 
phone diaphragm  are  caused  by  the  attraction  of  the  telephone 
magnet,  which  increases  as  the  product  of  the  current  in  the 
telephone  and  the  number  of  turns  in  the  windings.  As  the  cur- 
rent from  the  detector  is  very  small,  it  is  evident  that  a  large 
number  of  turns  must  be  used  to  secure  the  necessary  attraction, 
and  hence  the  telephone  becomes  one  of  high  resistance. 

Every  telephone  diaphragm  has  a  certain  natural  period  of 
mechanical  vibration  or  pitch.  When  the  incoming  signals  are  of 
the  same  pitch — that  is,  they  are  in  resonance  with  the  period  of 
the  diaphragm — these  signals  will  be  heard  louder  than  others  from 
transmitters  of  the  same  power  but  of  different  pitch.  In  some 
cases  the  natural  pitch  of  a  diaphragm  may  coincide  with  that  of 
the  signals,  and  thus  the  telephone  will  be  found  to  be  very  sensi- 
tive. The  pitch  of  the  diaphragm  can,  however,  be  changed  by 
changing  the  distance  between  it  and  the  magnet,  and  some  types 
of  telephones  are  supplied  with  adjustable  pole  pieces.  By  this 
means  it  is  possible  to  tune  the  telephone  to  mechanical  resonance 
with  the  spark  frequency  of  the  transmitter  and  often  increase  the 
loudness  of  the  signals. 

The  fixed  condenser  is  shunted  across  the  telephone  terminals 
in  order  to  provide  a  complete  circuit  for  the  oscillations  between 
the  secondary  condenser  terminals  without  having  to  flow  through 
the  telephones,  the  high  inductance  of  which  in  circuit  would  tend 
to  choke  back  the  oscillations  and  so  possibly  prevent  their  detec- 
tion. It  is  evident  that  a  very  large  condenser  can  not  be  used,  as 
it  would  serve  as  such  a  low-impedance  shunt  for  the  pulsating  cur- 
rents from  the  detector  that  no  current  would  flow  through  the 
telephone,  and  on  the  other  hand  a  very  small  condenser  can  not 
be  used,  as  it  would  not  allow  the  oscillations  to  flow  through  it. 
The  best  value  must  then  be  determined  by  trial  and  it  is  found 
in  practice  to  vary  slightly  with  the  spark  or  wave  train  frequency. 
With  the  high-resistance  telephones  in  general  use  the  capacity  of 
the  condenser  is  about  0.003  to  0.0035  mf.  for  low-frequency  trans- 
mitters, as  60  cycles,  and  about  0.002  to  0.003  mf.  for  high  fre- 
quencies, as  500  cycles.  In  some  cases  this  condenser  is  variable 
by  steps  so  as  to  be  able  to  adjust  to  different  spark  frequencies 
or  to  group  tuning,  as  it  is  sometimes  called.  By  the  use  of  such 
a  variable  condenser  and  of  a  telephone  with  adjustable  pole  pieces 
it  is  often  possible  to  increase  the  loudness  of  signals  and  the  selec- 
tivity of  the  circuits  without  making  changes  in  the  tuning. 


RADIOTELEGRAPHY 


387 


CALIBRATING  WAVE  LENGTHS  OF  RECEIVING  CIRCUITS  BY 
MEANS  OF  THE  WAVE  METER 

In  the  previous  illustrations  of  the  wave  meter  it  was  used  to 
receive  oscillations  from  a  transmitter  and  to  measure  its  wave 
lengths.  It  may,  however,  be  used  to  send  out  oscillations  of  known 
wave  lengths  of  comparatively  feeble  intensity  like  a  miniature 
transmitter.  Several  types  of  circuits  may  be  used  to  excite  the 
meter,  as  a  buzzer  shown  in  figure  70,  where  A  is  a  battery  of  not 
more  than  two  dry  cells,  B  is  the  buzzer,  and  LC  is  the  meter. 
This  circuit  is  sometimes  known  as  the  busier  method  of  excitation 
of  the  wave  meter,  which  thereby  becomes  a  source  of  slightly 
damped  oscillations.  The  action  of  the  buzzer  circuit  seems  to  be 
that  at  each  spark  at  the  buzzer  contacts,  the  meter  condenser  is 

B 


Ih 


FIG.  70.— BUZZEK  EXCITATION  CIRCUIT  FOR  WAVE  METER 
EMPLOYED   AS   A   TRANSMITTER 

charged  and  then  discharged  through  the  inductance  and  thus  sets 
up  oscillations,  independently  of  the  charging  circuit  in  a  manner 
similar  to  that  of  a  closed  circuit  as  charged  by  the  secondary  of 
the  A.  C.  transformer.  If  a  circuit  is  brought  near  the  coil  L  and 
loosely  coupled  with  it  the  meter  will  induce  in  the  circuit  oscilla- 
tions of  the  wave  length  or  frequency  corresponding  to  the  setting 
of  the  wave  meter  condenser.  The  circuits  of  a  station  receiver 
connected  to  the  station  antenna  may  be  calibrated  by  this  method. 
This  circuit  may  be  used  in  making  many  measurements  and 
tests  in  radio  work,  such  as  inductance,  capacity,  sensitiveness  of 
telephones,  detector,  etc. 


388 


MILITARY  SIGNAL  CORPS  MANUAL 


EXPLANATION  OP  SYMBOLS 

USED  IN  CIRCUIT  DIAGRAMS 


WVWW- 


A  COIL  HAVING  THE  PROPERTY 
OF  RESISTANCE 


A  VARIABLE  RESISTANCE 


A  COIL  HAVING   THE  PROPERTY 
OF  INDUCTANCE 


A  COIL  HA  VI NG  A  VARIABLE 
VALUE  OF  INDUCTANCE 


AN  OPEN  CORE  TRANSFORMER 


A  CLOSED   CORE 

TRANSFORMER 


A  TRANSMITTING  KEY 


AN  ADJUSTABLE 
REACTANCE  COtL 


AN  INDUCT/  VEL  Y  COUPL  ED 

OSCILLATION  TRANSFORMER 


A  FIELD  RHEOSTAT 


\\ 


A  CONDENSER  OF  F/XED 
VALUE: 


A  CONDENSER  OF  CONTINUOUSLY 
VARIABLE  CAPACITY 


RADIO  TELEGRAPHY 


389 


A  CONDENSER,  TH£  CAPACITY 

OF  WHICH  A5  ADJUSTABLE 

BY  STEPS. 


CfUS  OF  BATTERY  CONNECTED 
IN  SERIES 


ACONDUCTIVELY  COUPLED 

OSCILLATION  TRANSFORMER 


A  VARIOMETER  INDUCTANCE 


RHOTECTt  VE  RE3IS  TANCE  ROD 

<^ 

A 

SM* 
AMMETER 


VOLTMETER 


WATTMETER 


D.C.  ARMATURE 


A.C.  ARMATURE 


INCANDESCENT  LAMP 


RECEIVING  HEAD  TELEPHONE 


CRYSTALLINE  DETECTOR 


ELECTROL  YT/C OE-TECTCff. 


RADIO  APPARATUS  OF  THE  SIGNAL  CORPS 

Two  types  of  portable  field  sets  have  been  issued  by  the  Signal 
Corps.  The  smaller  size,  known  as  a  field  radio  pack  set,  is  fur- 
nished to  the  Organized  Militia  as  well  as  to  the  field  companies. 
The  range  of  these  sets  under  normal  conditions  is  about  25  miles 
over  land,  but  much  greater  over  water.  Thus  one  of  the  one- 
eighth  kilowatt  sets,  with  a  100-foot  mast,  at  Habana  has  worked 
with  the  naval  station  at  Key  West,  a  distance  of  about  110  miles. 

The  larger  size  of  field  sets,  known  as  a  wagon  set,  is  of  2- 
kilowatts  output  and  is  carried  on  a  two-chest  pintle  wagon,  one 
chest  with  the  engine  and  generator  and  the  other  with  the  trans- 
mitting and  the  receiving  apparatus.  The  range  of  these  sets  va- 
ries from  75  to  800  miles,  depending  on  favorable  weather  con- 
ditions, time  of  day  or  night,  character  of  the  land  between  the 
sets,  and  similar  considerations. 

FIELD  WAGON  SETS 

The  following  are  the  general  instructions  for  the  operation  and 
care  of  the  two-wagon  2-kilowatt  set: 

Engine. — The  engine  supplied  with  this  set  is  a  water-cooled, 
single-cylinder  gasoline  engine  with  a  normal  speed  of  1,500  R.  P. 
M.,  and  the  same  general  directions  as  to  care  and  operation  which 
apply  to  water-cooled  gasoline  engines  in  general  apply  in  this  case, 
and  the  principal  points  are  briefly  as  follows : 

Before  starting  make  sure — 

1.  That  the  water  tank  is  full. 

2.  That  all  bearings  have  been  oiled. 

3.  That  the  engine  has  sufficient  lubricating  oil  by  means  of  the 
stopcock  on  under  part  of  crank  case.     If  it  drips  when  opened, 
there  is  sufficient  oil. 

4.  That  there  is  sufficient  gasoline  in  the  tank  as  indicated  by 
the  gauge  on  the  front  of  the  tank. 

5.  That  the  main  switch  of  the  generator  is  open. 

390 


RADIO  APPARATUS 


391 


To  start — 

1.  Open  gasoline   feed  cock. 

2.  Prime  carburetor  by  plunger  on  top. 

3.  Set  the  governor  control  handle   (just  above  the  crank)  ver- 
tically, i.  e.,  halfway  across  the  scale. 

4.  Set  the  spark-control  lever  on  the  magneto  on  bottom  notch. 

5.  Crank. 
After  starting — 

1.  Make  sure  that  the  fan  is  running. 

2.  Close  main  switch. 

Speed :  The  speed,  as  indicated  by  the  tachometer  on  the  engine, 
is  controlled  by  the  position  of  the  governor  control  handle  (di- 
rectly over  the  crank)  and  by  the  position  of  the  spark  control 
lever  on  the  magneto  (at  the  right),  and  the  best  position  of  each 
for  any  particular  speed  is  best  and  easily  determined  by  experiment. 

To  shut  down  temporarily — 

1.  Open  main  switch  of  generator. 

2.  Press  button  on  front  of  magneto  until  engine  stops. 
To  shut  down  permanently — 

1.  Same  as  above. 

2.  Ditto. 


THE   I-'IELD   WAGOX   SET  OPEN   AND   READY   FOR  OPERATION 


392  MILITARY  SIGNAL  CORPS  MANUAL 

3.  Turn  off  gasoline. 

4.  In  cold  weather  empty  all  water  out  of  every  part  of  cooling 
system  by  means  of  the  cocks  provided  for  that  purpose. 

Generator. — The  alternating  current  generator  supplied  with  this 
set  is  of  the  inductor  type  with  the  field  and  armature  winding 
stationary,  and  has  therefore  no  brushes  or  sliding  contacts  of  any 
kind.  Its  normal  voltage  is  85.  The  exciter  is  an  ordinary  low. 
voltage  direct  current  machine.  The  voltage  of  the  alternating- 
current  generator  is  varied  by  means  of  the  rheostat  in  series  with 
its  field.  The  rheostat  is  located  in  the  lower  left-hand  corner  of 
the  front  part  of  the  instrument  wagon.  The  connections  between 
the  power  wagon  and  the  instrument  wagon  are  made  by  means  of 
a  flexible  armored  four-conductor  cable  having  the  sockets  so 
arranged  that  the  terminals  can  be  inserted  only  in  the  proper  man- 
ner, the  circuits  of  the  alternator,  exciter,  etc.,  being  shown  in 
figure  3. 

Transmitter  and  receiver. — The  connections  of  both  are  clearly 
shown  in  the  drawing  and  require  no  further  description. 

To  adjust  the  transmitter  for  any  wave  length  within  the  range 
of  the  set  proceed  as  follows,  assuming  that  the  desired  wave  length 
is  1,000  meters : 

1.  If  it  is  intended  to  send  at  full  power,  adjust  the  voltage  of 
the  generator  by  means  of  the  slide  rheostat  (at  the  left)  to  about 
85  volts. 

2.  If  it  is  intended  to  send  at  less  than  full  power,  short-circuit 
one  or  more  of  the  gaps  by  means  of  the  clips  provided  and  at  the 
same  time  reduce  the  generator  voltage  about  10  per  cent  per  gao 
short-circuited. 

3.  Set  the  primary  variometer   (at  the  left)   at  the  wave  length 
desired,  viz,  1,000. 

4.  Put  the  aerial-coil  plug  (at  the  right)   in  hole  No.  1,  marked 
680/1050.    This  adds  sufficient  inductance  to  the  aerial  to  bring  the 
final  adjustment  within  range  of  the  aerial  variometer. 

5.  Make  the  final  adjustment  with   the  aerial  variometer    (also 
on   the   right  and   on  one   side  of  the  aerial  coils)    by  turning  it 
slowly  up    from   zero   until  the   ammeter   in   the  aerial   or  ground 
circuit  indicates  a  maximum. 

6.  The  transmitter  is  now  adjusted   for  the  most  efficient  pro- 
duction and  radiation  of  the  wave  length  selected  when  used  with 
the  aerial  and  counterpoise   supplied   with  the   set. 

Receiver — To  receive,  close  the  large  double-pole  switch  at  the 
top  of  the  receiver. 

The  plug  holes  marked  Roman  numbers  (at  the  right  on  the  re- 
ceiver) are  connected  to  taps  on  the  aerial  or  primary  'coil.  The 
wave  range  of  this  coil  is  approximately  as  follows,  with  a  proper 
aerial : 


RADIO  APPARATUS 


393 


FIG.   1. -CONNECTIONS  OF  WAGON  SET 


394 


MILITARY  SIGNAL  CORPS  MANUAL 


Condenser    i 

witch    at— 

Short    waves 

Long   waves 

I   

Meters 
260-400 

Meters 
500-600     ' 

II    

310-510 

640-910 

Ill   . 

370-730 

900-1  410 

IV    

540-1,060 

1,270-2,150 

V    
VI    

1,860-3,080 
2,700-4,000 

The  turns  on  the  detector  or  loose  coupling  coil  are  variable 
by  means  of  the  switch  located  on  its  top,  the  wave  range  for  each 
tap  being  marked. 

Either  of  the  two  detectors  can  be  used  by  means  of  the  switch 
located  between  them. 

For  receiving  a  signal  of  a  known  wave  length  the  following 
procedure  can  be  recommended: 

1.  Use  tight  coupling. 

2.  Plug  in  on  the  aerial  coil. 

3.  Set  the  switch  on  the  detector  coil  at  about  '  'X=500/1000. " 

4.  Turn  the  condenser  very  slowly  over  the  entire  scale. 

5.  Change  the  plug  on  aerial  coil  and  repeat  No.  4.    When  sig- 
nals are  finally  heard,  the  coupling  and  the  position  of  the  switch 
on  the  detector  coil  are  varied  until  the  best  results  are  obtained. 

NOTE. — In  some  cases  two  combinations  of  the  aerial  plug  and 
condenser  give  almost  equally  good  results.  The  best  one  is  that 
in  which  the  larger  part  of  the  condenser  is  used  with  condenser 
switch  at  "  short  waves  "  and  vice  versa,  with  the  condenser  switch 
at  "  long  waves."  The  aerial  used  with  this  set  should  have  :i 
capacity  of  0.0011  mf  and  a  natural  period  of  450  meters. 

The  following  detailed  notes  on  the  circuits  and  operation  of  the 
set  have  been  found  useful  as  a  result  of  actual  work  in  the  field: 


POWER  CIRCUITS 

Referring  to  connection  diagram  Fig.  1,  it  is  seen  that  D.  OP 
leads  marked  3  and  4  go  to  both  receiving  switches  in  series,  it 
is  therefore  necessary  to  have  the  main  switches  of  both  receiving 
sets  in  the  same  position — that  is,  cut  off — when  sending,  even 
though  one  receiving  set  may  have  no  aerial  wire  connected  to  it. 
A  flash  due  to  the  breaking  of  this  D.  C.  circuit  will  be  seen  at 
the  rotary  switch  if  the  receiving  set  is  cut  in  before  the  engine 
is  stopped.  The  large  double-pole  switch  at  the  top  of  the  receiver 
when  closed  so  as  to  connect  the  receiver  to  the  aerial  and  counter- 
poise automatically  disconnects  the  sending  side  from  the  aerial 


RADIO  ATT. -I R ATI'S 


395 


and  counterpoise.  This  feature  is  not  indicated  in  the  diagram  of 
connections  where  the  receiving  set  when  cut  in  is  apparently 
shunted  by  the  sending  set. 

TRANSFORMER   PRIMARY   CIRCUIT 

From  A.  C.  lead  No.  1  to  the  primary  inductance,  to  the  snap 
switch,  to  the  ammeter,  to  the  primary  of  the  transformer,  to  the 
key,  and  via  A.  C.  lead  No.  2  back  to  the  generator.  The  voltmeter 
is  across  the  A.  C.  leads  as  shown.  If  the  voltmeter  shows  volt- 


Condenser 


FIG.    2.— CONNECTIONS   FOR    SENDING 

age,  but  upon  closing  the  key  no  spark  takes  place  at  the  spark 
gap,  the  snap  switch  in  the  primary  circuit  is  probably  open. 

The  voltage,  as  indicated  by  the  voltmeter,  must  never  be  more 
than  85.  If  it  is  desired  to  change  the  generator  frequency  (and 
the  pitch  of  the  note  emitted),  in  order  to  secure  greater  selectivity 


396 


MILITARY  SIGNAL  CORPS  MANUAL 


for  the  set  when  working  in  the  presence  of  other  sets  having  about 
the  same  generator  frequency,  the  engine  may  be  slowed  down  or 
speeded  up,  but  the  drop  or  rise  in  voltage  incident  thereto  must 
be  compensated  for  by  a  change  in  the  generator  rheostat,  so  that 
the  voltage  will  be  kept  constant  at  85  when  using  all  the  gaps  of 
the  spark  gap.  Any  violation  of  this  rule  will  cause  a  breakdown 
in  the  transformer. 

HIGH-FREQUENCY    CIRCUITS — TRANSMITTER 

Closed  oscillating  circuit. — This  consists  of  the  condenser,  vari- 
ometer, and  spark  gap.  It  is  to  be  noted  that  the  variometer  is 
common  to  both  closed  and  open  oscillatory  circuits,  and,  therefore, 


FIG.  3.— THE  GENERATOR  CIRCUITS 

that  changing  the  variometer  (which  is  the  one  at  the  left-hand 
side  of  the  chest  with  scale  divisions  in  wave  lengths  marked 
upon  it)  not  only  changes  the  period  to  which  the  closed  oscilla- 
tory circuit  is  tuned,  but  also  slightly  changes  the  tuning  of  the 
open  oscillatory  circuit.  A  word  of  caution  should  be  given  con- 
cerning the  switch  marked  "  Little "  and  "  Great "  which  throws 
the  coils  of  this  variometer  from  a  parallel  to  a  series  connection 
or  vice  versa.  This  switch  can  only  be  moved  to  the  right  or  left — 
to  "  Little  "  or  to  "  Great  " — when  the  index  is  directly  opposite 
the  dividing  line  between  the  red  and  the  white  divisions.  Any  at- 
tempt to  throw  this  switch  when  the  variometer  coils  are  in  any 
other  position  will  only  result  in  damage  to  the  switch. 


RADIO  APPARATUS 


397 


OPEN    OSCILLATORY   CIRCUIT 

This  consists  of  the  aerial,  aerial  or  loading  coils,  plug  for  cutting 
in  proper  coil,  the  aerial  variometer  (marked  from  zero  to  1800), 
the  variometer  common  to  both  closed  and  open  oscillatory  cir- 
cuits, the  hot-wire  ammeter,  and  the  counterpoise  or  ground. 

The  antenna  supplied  by  the  Signal  Corps  for  this  set  has  a 
natural  wave  length  of  450  meters  and  a  capacity  of  about  0.0011  mf. 
It  is  found  by  experiment  that  the  set  using  the  Signal  Corps 
80-foot  mast  and  rubber-covered  counterpoise  works  best  at  about 
1,000  meters,  where  the  antenna  hot-wire  ammeter  reads  about  T\i\ 
amperes. 

CODING  OF  WAVE  LENGTHS 

The  great  advantage  of  this  set  lies  in  the  fact  that  any  de- 
sired wave  length  from  675  to  2,220  meters  can  be  sent  out  at  will 
and  if  the  wave  length  is  changed  after  every  word  of  a  message, 
according  to  a  pre-arranged  code  of  wave  lengths — for  example,  the 
first  word  sent  with  700  meters,  the  next  with  2,100,  the  next  with 
1,400,  etc. — it  will  be  difficult  for  any  eavesdropping  operator  who 
has  not  the  wave-length  code  to  follow  the  changes  of  wave  length 
with  any  success.  Hence,  messages  may  sometimes  be  kept  confi- 
dential even  when  sent  in  plain  English.  This  will  take  consider- 
able drill  on  the  part  of  two  men,  the  operator  and  an  assistant, 
who  will  rapidly  make  the  necessary  changes  in  the  loading  coils 
and  variometers  at  a  signal  from  the  operator. 

The  first  step  will  be  to  make  experimental  determination  of 
the  combinations  of  loading  coils  and  variometers  necessary  to  pro- 

TABLE  1 


Wave   length 

Variometer 

Loading    coil 

Aerial 

variometer 

Amperes    on 
hot    wire 

700 

700 

675-1,080 

12 

6.9 

750 

750 

675-1,080 

20 

6.95 

800 

800 

675-1,080 

50 

7 

850 

850 

675-1,080 

80 

7.05 

900 

950 

675-1,080 

120 

7.1 

950 

900 

920-1,310 

4 

7.1S 

1,000 

1,000 

920-1,310 

10 

7.25 

1,050 

1,050 

920-1,310 

60 

7 

1,100 

1,100 

920-1,310 

90 

6.8 

1,150 

1,150 

920-1,310 

105 

6.6 

1,200 

1,200 

920-1,310 

130 

6.4 

1,250 

1,250 

1,240-1,510 

5 

6.2 

duce  the  best  radiation  for  every  wave  length  within  the  range 
of  the  set  and  to  set  them  down  in  the  form  of  a  table.  Thus, 
starting  with  700  meters,  put  the  left-hand  variometer  at  700,  put 


398  MILITARY  SIGNAL  CORPS  MANUAL 

the  plug  in  the  hole  marked  675-1,080,  and  then  slowly  move  the 
aerial  variometer  from  0°  toward  180°  until  the  hot-wire  ammeter 
shows  the  best  reading.  The  various  adjustments  can  then  be 
noted  in  a  table  for  future  reference,  thus  :  (The  figures  given  are 
not  the  actual  figures.  These  must  be  determined  for  each  set 
separately.)  Find  the  best  combination  for  every  SO  meters  increase 
in  wave  length  up  to  the  limit  of  the  set. 

LIMITATIONS    OF    SYSTEM    OF    CODING    WAVE    LENGTHS 

It  will  be  noted  that  there  is  one  best  wave  for  the  set,  namely, 
about  1,000  meters.  From  some  experiments  made  recently  at 
Fort  Leavenworth  it  is  'concluded  that  it  is  safe  to  state  that,  up 
to  about  75  miles  over  average  land,  the  falling  off  of  energy  due 
to  the  use  of  the  longest  wave  lengths  will  not  be  so  great  as  to 
prevent  the  use  of  any  wave  length  within  the  limits  of  the  set 
(675-2,220  meters),  but  that  beyond  that  distance,  up  to  the  ex- 
treme daylight  distance  of  the  set  (about  185  miles),  it  would  be 
safer  not  to  work  with  any  wave  length  greater  than  1,800  meters. 

Only  further  experiments  in  the  field  between  two  similar  sets 
working  at  gradually  increasing  long  ranges,  will  determine  the 
greatest  distance  at  which  the  whole  scale  of  sending  wave  lengths 
may  be  used. 

From  the  table  plotted,  different  codes  of  wave  lengths,  differ- 
ing by  many  meters  from  each  other,  may  be  agreed  upon,  to  be 
changed  daily  in  actual  work,  and  confided  to  all  operators  con- 
cerned. 

RECEIVING  CIRCUITS 

Primary  or  aerial  circuit. — One  lead  from  aerial  comes  through 
combination  switch  to  the  primary  of  the  transformer  (shown  on 
the  left  of  Fig.  4),  from  there  through  plug  contact  to  a  point 
on  the  little  switch  marked  "  Long  waves  " — "  Short  waves  " ;  and, 
if  the  switch  is  thrown  to  the  long-wave  side,  the  circuit  goes  direct 
to  the  ground ;  the  variable  condenser  being  then  in  parallel  with 
the  primary  of  the  transformer.  If  the  switch  is  thrown  to  the 
short-wave  side,  the  variable  condenser  is  in  series  with  the  aerial, 
the  primary  of  the  receiving  transformer,  and  the  counterpoise  or 
ground. 

The  secondary  or  detector  circuit  consists  of  the  secondary  of 
the  transformer  in  series  with  the  usual  stopping  condenser,  con- 
nected through  the  main  switch  to  the  detectors.  The  telephones 
are  in  shunt  to  the  stopping  condenser. 

The  detector  supplied  is  of  the  iron  pyrites  variety,  which  lacks 
the  sensitiveness  of  the  Perikon,  Any  other  detector  may  easily  be 


RADIO  APPARATUS 


399 


substituted   for  the   detectors   supplied   with   the  set,  the   range  of 
which  may  be  thereby  easily  increased. 

With  the  switch  thrown  to  "Long  waves"  the  operator  will  get 
the  best  results  when  using  a  small  number  of  degrees  of  the 
variable  condenser  and  as  large  primary  as  possible,  and,  vice  versa, 
with  the  switch  "Short  waves,"  which  places  the  variable  con- 
denser in  series  with  the  primary  coils.  The  largest  possible 
amount  of  capacity  of  the  variable  condenser  and  the  smallest 
amount  of  primary  inductance  should  be  used  for  maximum 
strength  of  signals. 


Var/'ab/e 
Condenser 


(Q) 
Telephone 

FIG.  4.— CONNECTIONS   FOR  RECEIVING 

The  combination  switch  which  is  used  primarily  to  cut  the  re- 
ceiving set  on  to  the  antenna  and  counterpoise  simultaneously  per- 
forms several  operations.  Opening  this  switch  disconnects  the 
receiving  set  from  the  antenna  and  counterpoise ;  automatically 
connects  sending  set  to  the  aerial  and  counterpoise ;  closes  D.  C. 
circuit  of  generator;  disconnects  deteqtors  from  secondary  of  re- 
ceiving transformer,  thus  opening  that  circuit  and  preventing 
detectors  from  being  affected  by  the  spark  when  sending,  and  also 
opens  the  primary  circuit  of  the  receiving  transformer.  As  the 
limits  of  the  various  coils  of  the  primary  and  secondary  are  marked, 
there  should  be  no  difficulty  about  setting  the  receiving  apparatus 
approximately  for  the  wave  length  of  a  station  whose  wave  length 
is  known.  The  operator  then  varies  his  condenser,  and  also  the 


400 


MILITARY  S1GXAL  CORPS  .U.IA7ML 


coupling  between  the  primary  and  secondary  of  the  receiving  trans- 
former, until  he  gets  the  best  adjustment.  Changing  the  coupling 
(that  is,  pulling  the  secondary  away  from  or  pushing  it  closer  to 
the  primary)  changes  the  -wave  length,  though  to  not  as  great  an 
extent  as  does  varying  the  condenser.  Some  stations  can  not  be 
heard  at  all  well  unless  the  secondary  coiL  is  pulled  some  distance 
away  from  the  primary.  Practice  is  the  best  guide  to  a  working 
knowledge  of  the  tuning  of  the  receiving  set. 

Figure  2   shows    simplified    schematic    diagram    of    the    trans- 
mitting circuits.     Figure  3  shows  the  generator  circuits. 

CALIBRATION     IN     WAVE    LENGTHS 

The  receiving  set  should  be  calibrated  so  as  to  locate  the  actual 
combinations  necessary  for  receiving  the  wave  lengths  sent  out  by  a 
similar  sending  set,  either  by  actual  tuning  to  another  set  sending 
out  successive  wave  lengths  differing  from  each  other  by  50  meters, 
as  outlined,  or  by  using  the  wave  meter  provided  with  each 
wagon  set  as  a  sending  device,  and  with  its  coupling  coil  held  near 
the  antenna  lead,  set  up,  consecutively,  different  wave  lengths  in 
the  antenna  and  make  adjustments  of  receiving  set  necessary  to  tune 
to  the  particular  wave  lengths  sent  out ;  then  compile  a  table  show- 
ing adjustments  of  condenser  switch,  primary,  secondary,  and  vari- 
able condenser  necessary  for  each  wave  length  in  turn,  so  that  the 
receiving  operator  can  at  once  adjust  his  receiving  apparatus  to  any 
desired  wave  length,  and,  by  quick  changes,  constantly  follow,  ac- 
cording to  prearranged  code,  the  message  sent  out  by  the  other 
station. 

It  is  recommended  that,  in  order  to  eliminate  one  adjustment  of 
the  receiving  set,  the  primary  and  secondary  of  the  receiving  trans- 
former be  kept  in  the  same  relative  positions  throughout ;  that  is, 
as  close  to  each  other  as  possible.  This,  while  possibly  sacrificing 
efficiency,  secures  simplicity.  The  receiving  operator's  chart  may 
be  arranged  as  follows : 

Best  receiving  adjustments  necessary  to  tune  to  wave  lengths 
used  by  similar  wagon-set  sending  wave  lengths  shown  in  Table  I. 

TABLE  II. 


Wave 
length 

Switch 

Primary 

Secondary 

Condenser 

700 

750 

Short  waves.  .  . 
Long  waves..  .  . 

370-730 
640-910 

500-1,000 
500-1,000 

80° 
40° 

And  so   forth   for  every  50  meters. 

Note. — The    condenser    adjustments    given    above    are    not    the    actual    onei 
necessary    for    wave    lengths    given. 


RADIO  APPARATUS  401 

Constant  drill  in  changing,  sending  and  receiving  adjustments, 
carried  on  between  two  or  more  similar  sets,  will  result  in  remark- 
able efficiency  and  rapidity,  and  the  time  necessary  for  transmission 
of  messages  will  be  found  to  be  but  little  increased  over  that  re- 
quired when  sending  on  a  single  wave  length. 

RECEIVING   BY   CODING   OF   WAVE   LENGTHS 

Two  complete  receiving  sets  are  provided  with  each  wagon  set, 
though  ordinarily  only  one  is  used.  Two  messages  from  different 
stations  may  be  copied  from  the  same  antenna  without  either  opera- 
tor hearing  the  message  copied  by  the  other.  To  do  this  it  is,  of 
course,  necessary  to  have  a  lead  from  the  aerial  running  to  each 
of  the  receiving  sets.  A  change  in  the  tuning  of  one  receiving  set 
will  call  for  a  slight  readjustment  of  the  other  receiving  set,  how- 
ever, in  order  that  the  latter  set  may  stay  in  tune  with  the  given 
wave  length. 

The  use  of  two  receiving  sets  in  parallel  makes  it  comparatively 
simple  to  follow  a  message  sent  according  to  a  pre-arranged  code  of 
wave  lengths,  for  it  is  perfectly  practicable  to  so  arrange  the  wave- 
length code  that  the  waves  of  any  length  within  certain  limits  will 
fall  within  the  limits  of  the  condenser  of  either  one  set  or  the  other, 
and  either  one  operator  or  the  other,  without  making  any  change  of 
adjustment  other  than  a  mere  movement  of  the  condenser  handle, 
will  have  his  apparatus  constantly  in  resonance  with  the  incoming 
waves. 

Thus,  let  us  say  that  in  the  code  agreed  upon,  which  includes  all 
wave  lengths  between  900  and  2,150  meters,  the  first  word  will  be 
sent  with  a  900-meter  wave,  the  next  with  2,100,  followed  by  1,500, 
1,850,  1,050,  2,000,  etc. 

The  two  sets  are  cut  in  at  the  receiving  station  and  are  each 
manned  by  an  operator.  Operator  No.  1,  at  the  left,  puts  the  plug 
in  the  hole  of  the  primary  of  his  receiving  set  marked  "900-1410," 
couples  his  primary  and  secondary  as  closely  as  possible,  throws  his 
receiving  switch  to  "Long  waves,"  and  puts  the  switch  of  the  de- 
tector coil  on  whatever  coil  will  give  him  the  strongest  signals. 
He  can  then,  by  merely  moving  his  condenser  from  0°  toward  180°, 
tune  his  set  to  any  desired  wave  between  900  and  1,410  meters,  and 
it  will  be  his  duty  to  copy  all  words  of  the  message  which  may 
fall  within  those  limits. 

Operator  No.  2,  on  the  right,  similarly  throws  his  switch  to 
"Long  waves"  and  plugs  in  primary  coil  marked  "1270-2150,"  and 
makes  the  other  adjustments  as  given  for  No.  1.  He  is  then  ready 
to  receive  any  wave  between  1,270  and  2,150  meters  by  merely  set- 
ting the  pointer  of  his  condenser  at  the  proper  number  of  degrees 
on  the  condenser. 


402  MILITARY  SIGNAL  CORPS  MANUAL 

From  Table  II,  prepared  as  before  described,  either  operator  can 
set  his  condenser  accurately  and  instantly  to  the  proper  reading  for 
any  desired  wave  length  within  limits ;  hence  when  the  message 
is  to  be  received  the  first  word  sent  as  per  schedule  at  900  meters 
is  copied  by  No.  1  operator,  who  has  his  pointer  at  the  proper  place 
on  the  condenser  scale ;  the  second  word  at  2,100  meters  by  No.  2, 
who  has  already  set  his  pointer  at  the  proper  place.  As  the  third 
word  is  sent  at  1,500  meters,  No.  2  readjusts  his  condenser  for  the 
next  word,  and  later  turns  the  pointer  to  the  proper  place  for  the 
next  word  at  1,850;  then  No.  1  comes  in  on  his  set  and  copies  the 
next  word  at  1,050  meters,  No.  2  the  next  at  2,000,  and  so  forth,  the 
words  being  placed  together  in  accordance  with  the  order  of  their 
receipt  so  as  to  make  a  complete  message. 

This  method  of  using  two  operators  saves  time  by  dispensing  with 
a  number  of  switch  and  plug  changes,  which  a  single  operator  would 
have  to  make  in  using  only  one  receiving  set. 

The  method  of  using  two  receiving  sets  tuned  as  described  could 
easily  be  worked  by  one  operator  who  could  wear  the  single  head 
receiver  of  one  set  on  one  ear  and  that  of  the  other  on  his  other  ear. 

All  these  methods  should  be  practised  continually  to  improve  the 
skill  of  the  operators. 

Care  must  be  taken  to  close  or  open  both  main  switches  of  the 
receiving  set  at  the  same  time  when  working  both  receiving  sets 
in  order  to  prevent  sending  into  one  of  the  receiving  sets  and 
burning  it  out. 

FIELD  RADIO  PACK  SETS 

The  smaller  size  of  portable  sets,  known  as  a  field  radio  pack 
set,  has  been  made  in  several  models  designated  by  the  number  of 
the  year  in  which  they  were  made.  Owing  to  the  rapid  improve- 
ment in  design  and  construction,  the  1912  model  has  become  prac- 
tically obsolete. 

1913  MODEL 

Radio  pack  set,  model  1913,  consists  of  the  following  units: 
1  operating  chest. 
1  hand  generator. 
1  mast. 

1  pack  frames,  set  (3  frames). 
1  tent. 

Each  unit  contains  component  parts  as  follows: 
Operating  chest : 

1  chest. 

1  resonance  transformer. 


RADIO  APPARATUS  403 

1  condenser. 

1  oscillation  transformer. 

1  sending  key. 

1  spark  gap. 

1  hot-wire  ammeter. 

1  switch. 

1  receiving  set. 

1  connecting  cord  for  generator   (4-conductor,  with  plugs). 

1  connecting  cord,  with  plug,   for  antenna. 

1  double-head  receiver. 

1  test  buzzer. 

1  tool  kit. 

1  extra   section    for   transformer   secondary. 

1  extra  set  crystals. 

1  canvas  case  for  receiver. 

1  connector,  4-wire   (lower  half),  generator. 

2  connectors,  2-wire   (lower  half),  antenna  and  counterpoise. 
1  copy  "Radiotelegraphy." 

Hand  generator: 

1  generator. 

2  cranks. 
1  stand. 

1  speedometer   (carried  in  operating  chest). 
1  cap  for  speedometer  opening. 
1  canvas  hood. 

Mast,  type  F.     (Type  D  mast  has  1  top,  1  bottom,  5  intermediate, 

and  3  extra  sections)  : 
1  top  section. 
1  bottom  section. 

8  intermediate  sections. 

4  intermediate  sections,   extra    (3  for  tent). 
1  antenna. 

1  counterpoise. 

9  carriers,  wire. 
4  pins,  antenna. 

2  hammers. 

1  set  adapters  for  tent  (4  pieces). 
1  bag,   antenna  and  counterpoise. 
1  bag,  accessories. 

Pack  frames,  set : 

3  frames   (1  set).     Each  frame  is  complete  with  cincha,  3  cincha 
straps  with  rings  and  snap  hooks,  and  2  straps  with  snap  hooks 
at  each  end. 


404  MILITARY  SIGNAL  CORPS  MANUAL 

Tent : 

1  tent. 
14  pins. 

2  guy  ropes. 

1  insulating  device. 

Complete  sets  should  be  designated  as  "radio  pack  sets,  com- 
plete," giving  year  and  serial  number,  and  should  be  so  carried  on 
property  returns,  invoices,  and  shipping  manifests. 

Incomplete  sets  should  not  be  so  designated,  but  units  in  them 
which  are  complete  should  be  designated  as  under  the  unit  heading 
above  and  units  that  are  not  complete  should  be  designated  as  un- 
der the  component  part  heading.  When  units  or  component  parts 
are  used  to  complete  sets  they  should  be  extended. 

Operating  chests  and  hand  generators  should  always  be  desig- 
natedlby  the  year  and  serial  number,  and  masts  by  the  type  letters. 

SECTIONAL   MAST 

The  new  type  F  sectional  mast  with  short  sections  is  superseding 
the  type  D  with  long  sections  as  the  stock  of  the  latter  becomes  ex- 
hausted, as  it  has  been  found  by  experience  that  a  mast  with  short 
sections  can  be  raised  more  easily  from  the  ground  than  one  with 
long  sections.  The  type  F  mast  equipment  consists  of  14  sections, 
each  4  feet  2  inches  long  or  5  feet  2  inches  over  all,  including  the 
coupling  tube.  The  10  sections  are  used  for  the  mast  itself,  3  sec- 
tions for  the  shelter  tent  when  erected,  and  1  extra  section  for  use 
in  case  one  of  the  others  becomes  unserviceable. 

When  starting  to  erect  the  mast,  the  four  antenna  wires  and  guys 
should  be  laid  out  on  the  ground  at  right  angles  to  each  other  and 
the  umbrella  insulator  put  on  the  upper  end  of  the  section  that  is 
not  provided  witfc  a  coupling  tube.  This  section  should  then  be 
raised  and  eight  more  sections  with  coupling  tubes  added,  section 
by  section,  the  tenth  and  last  section  being  the  one  provided  with 
the  insulator  fixed  at  the  bottom  end.  During  the  erection  the 
mast  should  be  kept  as  nearly  vertical  as  possible  by  the  men  hold- 
ing the  distant  ends  of  the  antenna  guy  ropes.  Owing  to  the  liabil- 
ity of  the  mast  to  buckle,  no  attempt  should  be  made  to  erect  the 
entire  mast  at  one  time ;  that  is,  by  coupling  all  sections  together 
and  raising  by  means  of  the  guys. 

ANTENNA   AND  COUNTERPOISE 

The  standard  antenna  is  of  the  umbrella  type  with  four  radiating 
wire,  each  85  feet  long,  suitably  insulated  at  the  open  ends  and 
held  as  nearly  horizontal  as  possible  by  guy  rope  extensions,  each 
85  feet  long,  the  outer  ends  of  Tvhich  are  made  fast  to  ground  pins. 


RADIO  APPARATUS  405 

The  standard  counterpoise  has  four  radiating  insulated  wires,  each 
100  feet  long,  laid  out  on  the  ground  under  the  antenna  wires.  Both 
antenna  and  counterpoise  wires  are  carried  on  hand  reels  for  con- 
venience in  packing  and  quick  reeling  and  unreeling  in  setting  up 
and  taking  down  the  mast. 

GENERATOR 

The  generator  is  a  hand-driven,  18-pole,  alternating-current  ma- 
chine having  an  intermittent  output  of  250  watts  at  110  volts  and 
500  cycles  at  a  speed  of  3333  R.  P.  M.  It  is  self-excited,  the  ex- 
citing current  for  the  fields  being  generated  by  a  small  shunt-wound 
direct-current  machine,  the  armature  of  which  is  mounted  on  the 
same  shaft  as  the  alternator  armature.  The  exciter  has  two  poles 
and  delivers  the  direct  current  at  about  110  to  150  volts.  The 
whole  machine  is  driven  by  two  handles,  which  should  be  turned 
at  the  rate  of  33  R.  P.  M.  to  give  the  necessary  armature  speed  of 
3333  R.  P.  M.,  the  combination  gear  having  a  ratio  of  about  100 
to  1.  The  direction  of  rotation  of  the  handles  must  be  as  shown 
by  the  arrow  on  the  top  of  the  gear  case,  as  otherwise  the  machine 
will  not  deliver  any  current.  The  whole  is  inclosed  in  a  dust-proof 
aluminum  case.  To  obtain  access  to  the  commutator,  remove  the 
flywheel,  taking  care  not  to  lose  the  key  on  the  flywheel  shaft; 
then  remove  the  large  brass  nut  and  the  aluminum  disk  held  in 
place  by  the  latter,  after  which  it  will  be  found  that  the  commu- 
tator is  readily  accessible.  To  remove  the  armature  from  the  ma- 
chine, proceed  as  above ;  then  take  off  the  casing  covering  the  spur 
gears  at  the  opposite  end  of  the  shaft,  and  the  gears  themselves; 
before  removing  the  armature  take  the  brushes  out  of  the  holders 
to  avoid  injuring  or  breaking  them. 

The  tension  on  both  sets  of  the  generator  brushes  should  be  kept 
as  light  as  possible  consistent  with  good  commutation.  A  small  in- 
crease in  the  friction  of  these  brushes  will  require  considerable  ad- 
ditional power  to  drive  the  machine.  Both  sets  of  brushes  can  be 
removed  when  necessary  through  openings  in  the  lower  part  of  the 
case,  the  D.  C.  exciter  brushes  being  at  the  flywheel  end  and  the 
A.  C.  brushes  at  the  opposite  end. 

A  canvas  cover  is  provided  for  the  generator,  which  should  be 
kept  on  at  all  times  when  the  generator  is  not  in  use. 

SPEED    INDICATOR 

A  speed  indicator  is  mounted  on  the  upper  part  of  the  gear  case 
in  sight  of  the  men  driving  the  machine  so  as  to  show  if  it  is  being 
driven  at  the  proper  speed,  at  which  time  the  red  line  on  the  mov- 
ing vane  coincides  with  the  black  index  or  arrow  at  the  window. 


406  MILITARY  SIGXAL  CORPS  MANtJAL 

The  vane  is  divided  diagonally  into  black  and  white  parts,  the  white 
showing  if  the  speed  is  too  iow  and  the  black  if  too  high. 

In  putting  the  speed  indicator  in  place  it  may  be  necessary  to 
turn  handles  slightly  so  as  to  permit  the  gears  to  engage. 

In  case  the  vane  of  the  speed  indicator  comes  on  the  underside 
when  the  indicator  is  screwed  into  place,  it  can  be  turned  into 
proper  position  after  loosening  the  depressed  set  screw  on  the 
threaded  part  fitting  into  the  case  and  then  tightening  the  set  screw 
again. 

In  making  the  set  ready  for  transportation,  the  speed  indicator 
should  be  removed  and  packed  in  its  proper  place  in  the  operating 
chest  and  the  opening  closed  with  the  brass  plug  provided. 


GEARING 

The  gearing  is  a  combination  planetary  worm-and-spur  type  of 
high  efficiency  when  in  proper  alignment.  The  high-speed  shafts 
have  ball  bearings  and  the  gears  run  in  grease  or  oil  so  as  to  reduce 
the  friction  as  much  as  possible.  The  gears  should  never  be  taken 
apart  unless  absolutely  necessary  to  replace  worn  or  broken  parts, 
and  then  only  by  an  experienced  person.  If  not  properly  reassem- 
bled, or  if  the  driving  gear  does  not  run  perfectly  true  with  the 
worm,  undue  friction  and  wear  will  result,  the  machine  will  be 
harder  to  turn  than  before,  and  the  gears  will  be  speedily  destroyed. 

The  gears  and  ball-bearings  can  be  lubricated  by  either  a  non- 
fluid  oil  or  a  light,  thin  oil,  such  as  Medium  Monogram,  but  both 
must  be  free  from  acid  and  water  to  prevent  rusting.  If  oil  is 
used  it  should  be  supplied  through  a  small  cap  on  the  opposite  side 
of  the  case  from  the  speed  indicator.  The  level  should  be  kept  not 
more  than  one-eighth  inch  above  the  lower  edge  of  the  glass  win- 
dow at  the  flywheel  end  of  the  gear  case;  if  kept  above  this,  the 
oil  will  overflow  to  the  lower  part  of  the  case  and  cause  trouble 
and  sparking  at  the  commutator  and  collector  rings.  The  same 
kind  of  oil  should  be  used  on  the  flywheel  shaft  through  the  small 
hole  on  the  upper  side  of  the  bearing. 

If  nonfluid  oil  is  used  it  should  be  supplied  through  the  opening 
where  the  speedometer  is  screwed  into  place.  Not  less  than  a  pint 
nor  more  than  a  quart  should  be  used  in  the  main  gear  case,  but 
only  a  small  amount  in  the  spur  gear  case  at  the  end  opposite  the 
flywheel,  as  otherwise  the  machine  will  turn  hard  on  account  of 
choking  the  gears  with  too  much  nonfluid  oil  in  the  narow  gear  case. 

With  the  exception  of  an  occasional  addition  of  oil,  the  machine 
should  run  for  months  without  attention.  If  the  oil  becomes  thick 
or  dirty,  the  gearing  should  be  washed  out  with  gasoline  and  re- 
filled with  clean  oil  without  dismantling. 


RADIO  APPARATUS 


407 


Care  must  be  taken  not  to  start  or  stop  the  machine  suddenly,  as 
this  may  strain  or  break  the  gears.  The  machine  must  not  be 
stopped  by  means  of  the  handles,  but  only  by  friction  on  the  fly- 
wheel. 


CONNECTIONS 


The  leads  from  the  armature  of  the  A.  C.  generator  are  directly 
connected  to  the  transformer  primary  by  means  of  the  heavy  pair 


THE  HAND  GENERATOR  WHICH  SUPPLIES  CURRENT  TO  THE  PACK 
WIRELESS   SET  OF   THE   SIGNAL   CORPS 

of  leads,  the  larger  plug  of  which  being  put  into  the  socket  at  the 
left-hand  end  of  the  operating  chest  marked  "Gen."  and  the  smaller 
plug  into  the  socket  on  the  underside  of  the  gear  case,  also  marked 


408  MILITARY  SIGNAL  CORPS  MANUAL 

"Gen."  The  sending  key  is  in  the  circuit  of  the  alternator  fields 
and  the  exciter  armature,  and  is  so  connected  by  means  of  the  light 
pair  of  leads,  the  larger  plug  of  which  being  put  into  the  socket  at 
the  left  end  of  the  chest  marked  "Fid."  and  the  smaller  plug  into 
the  socket  on  the  underside  of  the  case,  also  marked  "Fid."  By 
the  use  of  these  circuits,  the  electrical  load  on  the  machine  is 
limited  to  the  small  one  of  the  exciter  field,  except  when  the  key 
is  closed  in  sending.  Experiments  have  shown  that  twice  the  out- 
put of  the  former  machines  can  thus  be  obtained  with  practically 
no  more  tiring  effects  on  the  men  than  before. 

OPERATING  CHEST 

In  this  chest  is  mounted  the  transmitting  and  receiving  appara- 
tus, the  diagram  of  which  is  shown  in  Figure  5.  To  put  the  chest  in 
condition  for  sending,  connect  the  double  contact  plugs  of  the  leads 
from  the  hand  generator,  field,  antenna,  and  counterpoise  to  the 
receptacles  marked  "Gen.,"  "Fid.,"  "A,"  and  "C,"  respectively,  and 
the  four  variable  contact  clips  on  the  leads  from  the  condenser, 
spark  gap,  antenna,  and  hot-wire  ammeter,  to  the  four  points  on  the 
flat  spiral,  as  indicated  on  the  diagram,  making  sure  that  the  counter- 
poise clip  is  at  the  end  of  the  outside  turn.  Set  the  control  switch 
at  the  "sending"  or  lower  position.  Release  the  indicating  needle 
of  the  ammeter  by  turning  the  small  knurled  screw  at  the  left-hand 
side  of  the  upper  binding  post.  When  the  needle  is  free,  adjust  to 
zero  position  on  the  scale  by  means  of  the  small  knurled  screw  at 
the  right  side  of  the  upper  binding  post.  Set  the  variable  spark-gap 
contact  on  the  fifth  plate,  counted  from  the  left  end,  so  as  to  put 
four  gaps  in  circuit.  Start  the  generator,  and  when  the  proper  speed 
is  obtained  the  set  is  ready  for  sending. 

QUENCHED-SPARK      GAP 

The  spark  gap  used  in  this  set  is  made  up  of  several  copper  disks 
separated  by  mica  washers  about  0.01  inch  thick.  Its  action  is  to 
allow  all  of  the  energy  of  the  closed  oscillating  circuit  to  be  trans- 
ferred to  the  open  or  radiating  circuit  in  a  few  oscillations,  after 
which  the  spark  is  quenched  and  the  circuit  is,  in  effect,  open.  The 
activity  in  the  closed  circuit  having  ceased,  the  open  or  radiating 
circuit  continues  to  oscillate  at  its  own  period,  radiating  waves  of 
its  own  wave  length  without  any  retransfer  of  energy  to  the  closed 
oscillating  circuit,  which  continues  to  remain  open  until  a  spark 
breaks  down  the  gap  again  at  the  peak  of  the  next  alternation. 

In  order  to  work  at  maximum  efficiency,  the  quenched-spark  gap 
should  be  kept  cool.  It  is  for  this  reason  that  the  plates  are  pro- 
vided with  thin  cooling  flanges  having  a  large  surface  exposed  to 
the  air,  and  are  blackened,  a  black  body  cooling  more  rapidly  than 


RADIO  APPARATUS 


409 


FIG.  5.-WIRING  DIAGRAM,  FIELD  RADIO  PACK  SET.  MODEL  1913 


410 


MILITARY  SIGNAL  CORPS  MANUAL 


one  highly  polished.  If  the  gaps  have  become  too  hot,  as  by  keeping 
the  key  closed  for  a  long  time,  the  antenna  current  will  gradually 
decrease,  the  loss  at  times  being  as  much  as  40  per  cent,  so  that  it  is 
always  best  to  allow  the  gap  to  cool  before  using  again. 

The  gap  should  not  be  taken  apart  to  clean  its  sparking  surfaces 
like  an  ordinary  type  of  open  gap.  In  general  the  more  frequently 
such  a  gap  is  opened  the  more  unsatisfactory  may  be  its  operation. 
The  explanation  is  that  the  repeated  opening  of  the  gaps  introduces 


OHIO  SIGNAL  CORPS'  PACK  SET 


air  each  time,  and  that  with  free  exposure  to  air  the  sparking  sur- 
faces are  orroded  or  pitted,  but  that  when  kept  air-tight  they  are 
worn  smooth  and  clean  by  the  sparking  action.  Sometimes,  if  there 
is  a  flaw  in  one  of  the  plates  or  if  air  leaks  into  the  gap.  there  will 
be  a  noticeable  drop  in  the  antenna  current,  and  the  note  will  become 
poor.  When  it  is  believed  that  the  trouble  is  confined  to  one  or  two 


RADIO  APPARATUS  411 

gaps  it  is  possible  to  continue  sending  without  dismounting  the 
whole  gap  by  short-circuiting  the  bad  gaps  by  means  of  clips  pro- 
vided for  the  purpose,  in  which  case  as  many  new  gaps  must  be  put 
into  circuit  by  adjusting  the  movable  clip  to  the  right  as  were  cut 
out  by  the  short-circuiting  clips. 

The  gap  should  be  dismounted  only  when  the  trouble  has  been 
located  in  the  gap  and  it  has  been  found  impossible  to  remedy  it  b> 
short-circuiting  the  different  gaps  in  use.  The  gap  should  be  dis- 
mounted only  by  an  experienced  man,  who  should  clean  the  surfaces 
by  rubbing  them  face  down  on  fine  emery  cloth  or  paper  on  a  flat 
surface.  It  is  absolutely  necessary  that  both  the  bearing  surface 
and  the  sparking  surface  be  kept  true  and  plane,  as  shown  by  a 
straightedge. 

Great  care  should  be  exercised  in  reassembling  the  gap  to  set  the 
mica  washers  accurately  on  the  annular  surfaces  of  the  disk  and  to 
put  on  enough  tension  with  the  clamping  screws  to  render  all  of  the 
gap  spaces  air-tight. 


TUNING  OF  SENDING  SET 

The  tuning  of  the  closed  and  open  circuits  to  resonance,  and  the 
determination  of  the  correct  coupling  between  them  are  the  two  most 
important  adjustments  in  a  quenched  spark  transmitter.  In  the  pres- 
ent type  of  directly  coupled  set  with  a  flat  spiral  as  the  oscillation 
transformer,  these  adjustments  can  be  made  either  with  or  without 
the  help  of  a  wave  meter.  If  made  without  the  meter  the  .adjust- 
ments are  more  difficult  and  must  be  found  by  trial,  but  they  should 
satisfy  the  following  tests:  (1)  The  number  of  turns  in  the  closed 
circuit  should  be  chosen  so  as  to  give  the  desired  wave  length ;  (2) 
the  antenna  hot-wire  ammeter  should  show  the  maximum  reading 
that  can  be  obtained  by  adjusting  the  number  of  turns  in  the  open 
circuit  according  to  the  table  given  later;  and  (3)  the  note  as  heard 
in  the  telephones  of  the  receiving  set  should  be  clear  and  character- 
istic of  500  cycles.  These  adjustments  are.  in  general,  dependent  on 
each  other,  an  incorrect  change  in  one  seriously  affecting  all  the 
others ;  but  when  obtained  the  circuits  will  be  in  resonance  at  the 
desired  wave  length,  they  will  be  correctly  coupled,  and  the  closed- 
circuit  condenser  will  be  charged  and  discharged  regularly  once  per 
alternation. 

The  adjustments  should  be  made  as  follows:  Set  the  closed  and 
open  circuit  clips  on  the  turns  corresponding  to  the  desired  wave 
length.  These  turns  are  approximately  correct  with  the  standard 
antenna  and  should  be  used  in  beginning  to  make  the  adjustments. 
If  the  antenna  ammeter  reads  between  2.2  and  3.0  amperes  and  the 
note  is  clear  and  of  500  cycles,  then  the  adjustments  are  correct 


412  MILITARY  SIGNAL  CORPS  MANUAL 

and  the  circuits  properly  tuned.  If  the  ammeter  reading  is  low 
and  the  note  low  and  clear  or  low  and  ragged,  possibly  the  cir- 
cuits are  correctly  tuned,  but  there  are  too  many  gaps  in  circuit, 
and  the  condenser  is  being  charged  and  discharged  either  regularly 
or  irregularly  only  every  second  or  third  alternation.  Reduce  the 
number  and  see  if  this  change  gives  a  clear  500-cycle  note,  etc.  Simi- 
larly if  the  note  is  high  and  hissing,  the  condenser  is  being  charged 
and  discharged  more  than  once  per  alternation.  Increase  the  num- 
ber of  gaps  and  see  if  this  change  gives  a  clear  SOO-cycle  note,  etc. 
If  none  of  these  changes  give  the  correct  adjustment,  then  the  cir- 
cuits are  not  in  resonance,  or  the  coupling  is  wrong.  Move  one  of 
the  open-circuit  clips  to  see  if  the  correct  adjustments  can  be  ob- 
tained ; .  it  is  impossible  to  state  which  clip  should  be  moved  or  in 
which  direction.  If  the  change  of  one  clip  is  not  sufficient,  move 
both  open-circuit  clips  until,  by  repeated  trials,  the  correct  adjust- 
ments have  been  found.  If  possible,  leave  the  counterpoise  clip  on 
or  near  the  outside  turn,  so  that  it  will  be  at  ground  potential.  It 
will  be  found  that  the  character  of  the  note  will  be  changed  as  these 
various  changes  in  coupling  and  tuning  are  made,  but  the  clearest 
SOO-cycle  note  will  be  obtained  when  all  adjustments  are  correct  and 
the  circuits  properly  tuned.  After  the  adjustments  have  been  com- 
pleted at  this  wave  length,  tabulate  the  results  as  shown  and  repeat 
at  other  wave  lengths  within  the  range  of  the  spiral. 

Although  there  is  no  direct  test  that  can  be  applied,  except  with 
a  wave  meter,  to  determine  if  a  single  wave  length  is  being  radiated, 
yet  in  general  this  will  be  the  case  if  the  adjustments  satisfy  the 
tests. 

If  a  wave  meter  is  available  the  adjustments  are  much  easier  to 
make,  and  they  should  satisfy  the  following  tests:  (1)  A  single 
sharply  denned  wave  should  be  radiated  of  the  desired  wave  length, 
(2)  the  antenna  ammeter  and  the  signals  in  the  telephones  of  the 
meter  should  show  the  maximum  reading  and  signals  obtainable 
under  the  first  condition,  and  (3)  the  note  should  be  clear  and  of  500 
cycles. 

It  will  probbaly  be  best  to  use  the  wave  meter  with  a  detector  or 
helium  tube,  because  it  will  be  impossible  to  turn  the  hand  gener- 
ator at  a  sufficiently  constant  speed  to  obtain  steady  readings  on 
the  wattmeter  and  hence  difficult  to  determine  the  resonance  point 
and  wave  length. 

The  adjustments  for  tuning  should  be  made  as  follows:  Discon- 
nect the  open-circuit  clips,  and  set  the  closed-circuit  clips  on  the 
turns  corresponding  to  the  desired  wave  length.  Measure  the  wave 
length  according  to  the  instructions  just  given  to  make  certain  that 
it  is  correct.  Set  the  open-circuit  clips  on  the  turns  given  in  the 
table,  and,  with  the  wave  meter  near  the  antenna  or  counterpoise 
wires,  but  not  near  the  spiral,  see  whether  there  is  one  wave 


RADIO  APPARATUS  413 

length  or  two  in  the  meter.  If  there  is  a  single  sharply  defined 
wave  length,  and  the  antenna  ammeter  reading  can  not  be  in- 
creased by  slight  changes  of  either  or  both  ~of  the  open-circuit 
clips  and  the  note  is  clear  and  of  500  cycles,  then  the  adjustments 
are  correct  and  the  circuits  properly  tuned.  If  there  is  only  one 
wave  length,  but  the  antenna  ammeter  reading  is  low  and  can  not 
be  increased  by  slight  changes  in  the  open-circuit  clips,  then  the 
coupling  is  too  loose  and  must  be  tightened.  Move  the  open-circuit 
turns  in  use  inward  as  a  whole,  by  moving  both  clips  inward  and 
slightly  increasing  the  number  of  turns  in  circuit  to  allow  for  the 
decrease  in  their  diameter,  until  with  a  single  sharply  denned  wave 
length  the  antenna  ammeter  reading  is  a  maximum,  etc.,  as  before, 
in  which  case  the  circuits  are  properly  tuned.  If  the  note  is  low, 
decrease  the  number  of  gaps;  if  high  and  hissing,  increase  the  num- 
ber as  previously  described.  If,  however,  there  are  two  wave 
lengths,  move  one  or  both  of  the  open-circuit  clips,  but  it  is  im- 
possible as  in  the  previous  case  to  state  which  clip  or  in  which  direc- 
tion, until  by  repeated  trials  it  has  been  found  that  there  is  a  single 
sharply  defined  wave  length,  a  maximum  antenna  ammeter  reading, 
etc.,  as  before,  in  which  case  the  circuits  are  properly  tuned. 

After  the  adjustments  have  been  completed  at  this  wave  length 
repeat  at  other  wave  lengths  as  before  and  tabulate  the  results. 

If  the  one-eighth  or  one-fourth  kilowatt  motor-generator  or  the 
engine-driven  one-fourth  kilowatt  generator  supplied  by  the  Signal 
Corps,  is  available,  it  should  be  used  as  the  source  of  the  500-cycle 
current  because  its  voltage  will  be  much  steadier  than  that  of  the 
hand  generator.  When  the  motor-generator  set  is  used,  the  A.  C. 
armature  and  the  D.  C.  motor  should  be  protected  from  ''kickbacks" 
due  to  the  use  of  the  sending  key  in  the  alternator  fields,  by  two  high- 
resistance  carbon  rods  mounted  on  suitable  bases  to  be  connected 
as  follows :  The  end  terminals  of  one  rod  to  the  two  A.  C.  leads 
close  to  the  machine ;  the  end  terminals  of  the  other  rod  to  the  two 
main  line  D.  C.  leads  close  to  the  machine,  and  the  middle  points  of 
both  rods  to  be  connected  together  and  this  common  point  grounded 
on  the  frame  of  the  machine. 

The  constant  speed  of  the  motor  generator  makes  it  possible  to 
get  steady  readings  on  the  wattmeter  of  the  wavemeter,  and  hence 
easy  to  find  the  resonance  point  and  wave  length.  It  may  also  be 
more  convenient  than  a  detector  because  it  is  often  difficult  to  keep 
a  detector  point  in  sensitive  adjustment  on  account  of  the  nearness 
of  the  spark  gap  and  to  determine  the  resonance  point  on  account  of 
the  continuous  note  in  the  telephone.  However,  the  detector  and 
helium  tube  can  be  used  if  desired ;  the  circuits  will  be  correctly 
tuned  no  matter  what  means  are  used  for  determining  resonance. 
The  circuits  should  be  adjusted  to  resonance,  etc.,  as  described  in 
previous  paragraphs. 


414 


MILITARY  SIGNAL  CORPS  MAXUAL 


In  some  cases  it  may  be  convenient  to  use  the  following 
slight  modification  of  the  method  described.  Disconnect  the 
transformer  secondary  from  the  closed  circuit  and  connect  it  to 
the  two  terminals  of  a  small  zinc  or  brass  spark  gap,  one  of 
which  is  connected  to  the  counterpoise  and  the  other  to  the 
standard  antenna.  Measure  this  wave  length,  which  will  be  the 
fundamental  wave  length.  Next  insert,  say,  two  turns  of  the 
spiral,  Nos.  28  to  30,  counting  the  turns  from  the  inside  turn 
outward,  in  series  with  the  antenna,  and  measure  this  wave 
length.  Continue  in  this  manner  until  all  wave  lengths  are 
measured  within  the  range  of  the  spiral  and  tabulate.  Next 
make  the  standard  connections,  setting  the  open-circuit  clips  on 
the  turns  corresponding  to  the  desired  wave  length,  as  just  ob- 
tained. Set  the  closed-circuit  clips  on  the  turns  given  in  the 
table,  which  follows — "Short  Waves,"  "Long  Waves" — and 
make  the  necessary  adjustments  by  moving  these  clips  until  it 
has  been  found  by  trial  with  the  wavemeter  that  there  is  a 
single  sharply  defined  wave  length,  maximum  current  in  the 
antenna,  etc.,  as  before.  Tabulate  these  results  and  repeat  for 
wave  lengths  within  the  range  of  spiral.  In  this  case  the  closed 
circuit  is  tuned  to  the  open  circuit,  whereas  in  the  previous 
case  the  open  circuit  was  tuned  to  the  closed  circuit,  but  the 
same  tuning  points  will  be  found  for  the  same  wave  length,  which- 
ever method  of  tuning  is  used. 

It  is  impossible  to  use  exactly  the  same  method  as  in  this 
table,  in  which  the  number  of  turns  for  a  given  wave  length  is 
determined  for  both  the  primary  and  secondary  circuits,  after 
which  the  principal  adjustment  is  one  of  coupling,  because  the 
number  of  turns  in  the  primary  circuit  of  the  spiral  at  any 
wave  length  will  depend  on  the  part  of  the  spiral  which  is  in- 
cluded in  the  circuit,  and  hence  it  will  vary  with  every  com- 
bination of  turns.  It  is  for  this  reason  that  the  primary  tuning 
and  coupling  must  both  be  found  by  trial. 

OPEN-CIRCUIT  AND   CLOSED-CIRCUIT  TUNING 


Wave  length 

Antenna 

Counterpoise 

Meters 
300 

Turn    No. 
26H 

Turn    No. 
30 

325 

2VA 

30 

350 

22% 

30 

375 

20% 

30 

400 

185^ 

425 

16* 

Turns  to  be  counted  from  the  inside  turn  outward. 


K.1DIO  .\ri\\R.lTUS 


415 


Wave    length 

Closed-circuit 
clips 

Open-circuit 
clips 

Meters 

Turns 

Turns 

300 

8  and  12% 

26?4  and  30 

325 

8  and  13% 

24^  and  30 

350 
375 

8  and  13^6 
8  and  14% 

22%  and  30 
20%  and  30 

400 

8  and  14f£ 

18^4  and  30 

425 

Sand  15% 

16^  and  30 

Turns  counted  from  the  inside  turn  outward. 

Although  a  transmitting  set  using  the  flat  spiral  oscillation 
transformer  is  not  as  easily  tuned  as  some  other  types,  yet 
when  the  adjustments  have  once  been  made  and  tabulated  it  is 
practically  as  efficient  as  other  types.  It  has  the  advantage  of 
being  one  of  the  simplest,  most  rugged,  and  compact  forms 
which  can  be  installed  in  a  field  set. 


RECEIVING   SET,  TYPE  B 

The  receiving  set  consists  of  an  inductively  connected  trans- 
former with  broadly  tuned  secondary  circuits,  galena,  or  other 
similar  detector,  high-resistance  telephones,  etc.,  provided  with 
the  necessary  switches  for  tuning  to  different  wave  lengths. 
The  primary  circuit  includes  the  antenna,  primary  coil,  series 
condenser  or  not  as  may  be  needed,  and  counterpoise.  The 
antenna  is  connected  to  the  primary  coil  through  switches 
which  put  into  circuit  a  variable  number  of  turns,  steps  of  10 
turns  being  inserted  by  one  dial  switch  and  single  turns  by  the 
other.  The  total  number  of  primary  turns  is  thus  the  sum  of 
the  numbers  on  the  two  dials  indicated  by  the  two  switch  arms, 
which  can  be  varied  by  single  turns  from  one  to  the  whole 
number  in  the  coil.  For  wave  lengths  shorter  than  the  funda- 
mental wave  length  of  the  antenna,  a  fixed  condenser  is  in- 
serted in  series  with  the  primary  coil  by  throwing  the  switch 
near  the  binding  post  marked  "G"  to  the  position  "In,"  as 
shown  in  Figure  5.  For  the  longer  wave  lengths  the  switch  is 
thrown  to  the  other  position,  short-circuiting  the  condenser, 
and  thus  leaving  only  the  coil  in  circuit.  The  secondary  circuit 
includes  the  secondary  coil,  detector,  and  the  stopping  con- 
denser shunting  the  telephones.  The  coil  is  variable  only  by 
sections,  marked  "100,"  "200,"  etc.,  the  smaller  numbers  to  be 
used  as  the  shorter  wave  lengths  and  the  larger  ones  as  the 
longer  wave  lengths.  The  position  of  the  secondary  coil  with- 
in the  primary — that  is,  the  coupling — is  variable,  and  for  the 


416  MILITARY  SIGNAL  CORPS  MANUAL 

sake  of  convenience  a  scale  is  provided  so  as  to  be  able  to  note 
the  different  adjustments.  The  coupling  is  closest  when  the 
secondary  is  inside  the  primary,  in  which  case  the  scale  reading 
is  0,  and  vice  versa,  the  coupling  is  loosest  when  the  secondary 
is  drawn  outside  the  primary  and  the  scale  reading  is  40. 


FIELD  WIRELESS  STATION  IN  OPERATION,  WITH 

POWER  FOR  TRANSMISSION  OF  MESSAGES 

BEING  SUPPLIED  BY  HAND  GENERATOR 


RADIO  APPARATUS 

SHORT  WAVES 

Primary  condenser  in  scries 
(Switch  on   "In"'  contact.) 


417 


Wave 
length   (in 
meters) 

Primary 
turns 

Secondary 
turns 

Coupling 
scale 

200 

18 

100 

20 

300 

26 

200 

20 

400 

36 

200 

20 

500 

47 

300 

20 

600 

60 

300 

20 

700 

74 

400 

25 

800 

88 

400 

30 

Etc. 

Etc. 

Etc. 

Etc. 

LONG  WAVES 

Primary   condenser  short-circuited 
(Switch    not    on    "In"    contact.) 


Wave 

length   (in 
meters) 

Primary 

turns 

Secondary 
turns 

Coupling 
scale 

300 

24 

200 

20 

400 

30 

200 

20 

500 

38 

300 

20 

600 

46 

300 

20 

700 

56 

400 

25 

800 

65 

400 

30 

900 

76 

400 

30 

1,000 

91 

400 

25 

1,100 

107 

400 

25 

1,200 

125 

400 

30 

1,300 

144 

400 

25 

1,400 

162 

400 

25 

Etc. 

Etc. 

Etc. 

Etc. 

TUNING  OF   THE  RECEIVING    SET 

First,  the  detector  must  be  adjusted  to  a  sensitive  point  by 
means  of  the  test  buzzer,  the  note  of  which  should  be  clearly 
heard  in  the  receiving  telephones  when  it  is  held  near  the  an- 
tenna or  counterpoise  wires  or  the  coil  windings.  When  the 
wave  length  of  the  sending  station  is  known,  the  number  of 
turns  in  the  primary  and  secondary  coils  and  the  coupling 
should  be  set  according  to  the  values  in  the  above  table,  which 
will  be  approximately  correct  for  all  sets  using  the  standard 


418  MILITARY  SIGNAL  CORPS  MAX  UAL 

antenna.  When  the  wave  length  is  unknown,  then  signals  can 
be  found  only  by  repeated  trials  of  different  combinations  of 
turns  and  couplings,  in  which,  however,  consistent  sets  of  values 
may  be  taken  from  the  table.  When  once  the  signals  have  been 
heard  such  further  adjustments  of  primary  and  secondary  turns 
and  coupling  should  be  made  as  will  give  the  maximum  sound 
in  the  telephones.  In  general  it  will  be  found  that  when  there 
is  interference  or  static  troubles  the  sharpest  tuning  and  the 
best  protection  from  interference  will  be  obtained  when  the 
loosest  coupling  is  used;  that  is,  when  the  secondary  is  pulled 
out  as  far  as  possible  and  the  desired  station  is  still  heard.  It 
will  be  noticed  that  for  some  wave  lengths  there  are  two  dif- 
ferent possible  combinations  in  the  primary  circuit,  either  with- 
out a  condenser  and  a  few  primary  turns  or  with  a  condenser 
and  more  primary  turns.  It  is  impossible  to  tell  which  combi- 
nation is  the  better  without  actual  trial.  In  general  the  best 
coupling  between  the  circuits  will  vary  with  the  damping  of 
the  transmitting  station,  close  coupling  being  possible  with 
highly  damped  transmitters,  and  loose  coupling  necessary  with 
feebly  damped  transmitters. 

In  changing  the  coupjing  between  the  two  circuits  by  means 
of  the  handle  on  the  secondary  coil  care  must  be  taken  to  see 
that  the  contacts  on  the  various  studs  are  not  loosened,  as 
otherwise  the  signals  may  be  lost  entirely  or  the  tuning  made 
much  broader  on  account  of  high  resistance  that  may  be  intro- 
duced at  these  contacts. 

If  the  receiver  is  used  with  the  standard  antenna  and  signals 
are  being  received  from  an  unknown  station,  the  table  of  wave 
length  can  be  used  to  determine  approximately  the  wave  length 
of  the  unknown  station. 

SHELTER    TENT 

This  tent  is  similar  in  dimensions  and  construction  to  the 
standard  "common"  wall  tent  issued  by  the  Quartermaster's  De- 
partment, but  is  made  of  lighter  material  and  is  hot  provided 
with  ridge  pole  or  uprights.  In  erecting  the  tent  the  extra 
sections  furnished  with  the  mast  should  be  used  as  the  ridge 
pole  and  uprights  as  follows :  One  hollow  section,  one  plug, 
and  one  extension  piece  for  the  ridge,  and  one  section,  one 
extension  piece  with  spike  for  each  upright.  The  method  of 
erection  is  illustrated  in  Figure  6. 

INSULATING    DEVICE 

A  device  is  provided  for  use  in  insulating  the  antenna  when 
the  shelter  tent  is  used  in  damp  weather,  consisting  of  a  square 


RADIO  APPARATUS 


419 


piece  of  sheet  rubber  with  small  marginal  holes  for  lacing  into 
the  ventilator  at  either  end  of  the  tent,  and  a  tube  attached  to 
the  center  for  admitting  the  antenna  lead.  When  in  use,  suf- 
ficient slack  should  be  left  in  the  antenna  lead  to  form  a  drip 
loop  outside  of  the  tent,  and  if  found  necessary  a  piece  of 
heavy  insulated  wire  can  be  used  as  a  leading-in  wire. 

PACKING 

The  set  is  normally  packed  on  three  mules,  but  in  emergency 
may  be  packed  on  two.  In  normal  packing  the  first  mule 
carries  the  generator  and  six  sections  of  the  mast.  The  second 
mule  carries  the  operating  chest,  four  sections  of  the  mast,  an- 
tenna, counterpoise,  accessories,  bag,  etc.  The  third  mule 
carries  the  tent,  with  tent  pins  and  extension  pieces  folded  in- 
side, four  sections  of  the  mast,  flag  kit,  lanterns,  etc.  In 
emergency  packing  with  two  mules,  the  first  mule  carries  the 
generator  and  10  sections  of  the  mast,  and  the  second  the 
operating  chest,  four  sections  of  the  mast,  antenna,  counter- 
poise and  tent. 


-SPIKC 


SP/KC- 


i::~-:::m:: .-::: 


v_ 


RIDGE  POLE  EXTENSION  PIECE- 


SECTION 


-TENT  POLE.   EXTENSION  PIECE 


TENT  POLE.    EXTENSION  PICCC- 


SECTION 


MAST  SECTION - 


FIG.  6— METHOD  OF   ERECTING   SHELTER   TEXT 


420  MILITARY  SIGNAL  CORPS  MANUAL 

1915    RADIO   PACK    SET 

The  1915  set  is  similar  to  the  1913  type  and  in  general  the 
same  instructions,  etc.,  apply  to  it.  It  consists  of  the  following 
tutitt: 

1  operating  chest. 

1  hand  generator. 

1  mast. 

1  pack  frames,  set  (3  frames). 

1  tent. 

Each  unit  contains  component  parts  as  follows: 

Operating  chest : 
1  chest. 

1  resonance  transformer. 
1  condenser. 

1  oscillation  transformer. 
1  sending  key. 
1  spark  gap. 
1  hot-wire  ammeter. 
1  switch 
1  receiving  set. 

1  connecting  cord  for  generator  (4-conductor,  with  plugs). 
1  connecting  cord  with  plug,  for  antenna. 
1  double-head  receiver. 
1  test  buzzer. 
1  tool  kit. 

1  extra  section  for  transformer  secondary. 
1  extra  set  crystals. 
1  canvas  case  for  receiver. 

1  connector,  4-wire  (lower  half),  generator. 

2  connectors,  2-wire  (lower  half),  antenna  and  counterpoise. 
1  flexible  connector  for  antenna  inductance. 

1  connector,  2-wire,  small,  for  receiving  set. 

2  spring  hooks. 
4  legs  for  chest. 

1  copy  "Radiotelegraphy." 

Hand  generator : 

1  generator. 

2  cranks. 
1  stand. 

1  speedometer  (carried  in  operating  chest). 
1  cap  for  speedometer  opening. 
1  canvas  hood. 


RADIO  APPARATUS  421 

Mast,  type  F.    (Type  D  mast  has  1  top,  1  bottom,  5  intermediate 
and  3  extra  sections)  : 

1  top  section. 

1  bottom  section. 

8  intermediate  sections. 

4  intermediate  sections,  extra  (3  for  tent). 
1  antenna. 

1  counterpoise. 

9  carriers,  wire 
4  pins,  antenna. 

2  hammers. 

1  set  adapters  for  tent  (4  pieces). 
1  bag,  antenna  and  counterpoise. 
1  bag  accessories. 

Pack  frames,  set: 

3  frames   (1   set).     Each  frame  is   complete  with  cincha,  2 
cincha  straps  with  rings  and  snap  hooks,  and  2  straps  with 
snap  hooks  at  each  end. 

Tent. 

1  tent. 
14  pins. 

2  guy  ropes. 

1  insulating  device. 

Complete  sets  should  be  designated  as  "radio  pack  sets,  com- 
plete," giving  year  and  serial  number,  and  should  be  so  carried  on 
property  returns,  invoices,  and  shipping  manifests. 

Incomplete  sets  should  not  be  so  designated,  but  units  in  them 
which  are  complete  should  be  designated  as  under  the  unit  heading 
above  and  units  that  are  not  complete  should  be  designated  as  under 
the  component  part  heading.  When  units  or  component  parts  are 
used  to  complete  sets  they  should  be  extended. 

Operating  chests  and  hand  generators  should  always  be  desig- 
nated by  the  year  and  serial  number,  and  masts  by  the  type  letters. 

The  essential  differences  in  the  two  models  are  in  the  hand 
generator,  the  transmitting  oscillation  transformer  and  the  re- 
ceiving set,  a  brief  description  of  which  will  be  given. 

HAND   GENERATOR 

The  1915  generator  is  a  24-pole  machine,  with  a  speed  of  5,000 
R.  P.  M.  The  ratio  of  the  gearing  is  100  to  1,  as  in  the  1913  ma- 
chine, so  that  the  speed  of  the  handles  must  be  50  R.  P.  M.  At 
this  higher  speed  less  pull  is  required  on  the  handles  and  the 


422  MILITARY  SIGNAL  CORPS  MANUAL 

tiring  effect  of  the  men  is  less  than  33  R.  P.  M.  of  the  other 
machine. 

On  account  of  the  higher  speed  great  care  must  be  taken  to 
keep  the  D.  C.  commutator  clean  and  the  brushes  properly  fit- 
ted to  it.  Failure  of  a  machine  to  generate  current  is  almost 
always  due  to  a  dirty  commutator. 

Only  a  non-fluid  oil  should  be  used  for  lubrication  of  the 
gears  and  ball  bearings,  and  in  the  same  quantity  as  in  the  1913 
machine. 

OSCILLATION  TRANSFORMER 

The  oscillation  transformer  consists  of  two  open  spirals  in- 
ductively coupled  and  a  third  spiral  which  is  to  be  used  as  an 
antenna  inductance  for  obtaining  longer  wave  lengths.  This  in- 
ductance is  inserted  between  the  oscillation  transformer  and 
the  antenna  by  transferring  the  long  flexible  lead  from  the 
open  circuit  spiral  to  the  inductance  which  is  in  turn  connected 
to  the  oscillation  transformer  by  a  short  flexible  connection. 
Care  must  be  taken  to  see  that  these  added  turns  do  not  oppose 
the  turns  of  the  oscillation  transformer ;  that  is,  the  inside  turns 
of  one  should  be  connected  to  the  inside  turns  of  the  other. 

Ordinarily  the  antenna  in  luctance  will  not  be  in  the  circuit 
except  a  few  inches  from  the  iid  of  the  chest. 

The  wiring  diagram  is  shown  in  Figure  7,  in  which  the  heavy 
wave  lengths,  and  the  dotted  lines  from  it  to  the  antenna  in- 
ductance and  antenna  are  for  the  longer  waves. 

The  open  and  closed  circuits  of  the  oscillation  transformer 
are  electrically  joined  together  at  their  base,  to  which  the 
counterpoise  is  connected  through  the  control  switch  and  am- 
meter. This  method  of  construction  reduces  the  number  of 
movable  contacts  from  four  to  two  and  also  has  the  advantage 
that  the  outside  metal  rings  may  be  handled  without  danger  of 
shock. 

To  put  the  set  into  operation :  Connect  the  "Gen,"  "Fid,"  etc., 
plugs  into  the  corresponding  sockets ;  connect  the  short  flexible  wire 
from  the  rear  binding  post  of  the  closed  circuit  condenser  to  the 
small  angle  piece  extending  out  at  right  angles  from  the  base  of  the 
oscillation  transformer ;  connect  the  long  wire  at  the  opposite  end 
of  the  condenser  to  the  primary  or  closed  circuit  spiral,  inserting 
the  number  of  turns  corresponding  to  the  desired  wave  length, 
counting  the  turns  from  the  outside  turn  inward ;  connect  the  wire 
from  the  control  switch  to  the  open  circuit  spiral,  the  exact  number 
of  turns  to  be  found  later  by  trial.  The  other  end  of  the  spiral 
is  already  connected  to  the  counterpoise  through  the  antenna  am- 
meter. 


RADIO  APPARATUS  423 

In  tuning  the  circuits  the  two  spirals  should  be  swung  apart  from 
8  to  10  inches.  After  the  two  circuits  have  been  brought  into 
resonance,  as  indicated  by  the  greatest  deflection  of  the  hot  wire 
ammeter,  the  coupling  of  the  two  circuits  should  be  increased  or 
made  tighter  by  gradually  swinging  the  spirals  closer  together  until 
the  ammeter  deflection  just  begins  to  decrease.  If  a  wave  meter  is 
available  or  a  distant  station  assists  in  the  test,  a  single  wave  length 
or  "hump"  should  be  radiated  and  a  clear  note  obtained,  the  number 
of  gaps  being  adjusted  if  necessary  as  previously  described.  Care 
should  be  taken  not  to  have  too  close  a  coupling. 

When  the  standard  closed-circuit  condenser  and  oscillation  trans- 
former are  used  the  wave  lengths  are  very  approximately  given  in 
the  following  table : 

Wave  lengths  of  primary  or  closed  oscillating  circuit. 

Number  of 

primary 
Wave  lengths  in  meters:  turns. 

300 2 

400 3'/2 

500 5 

600 6y2 

700 8^ 

800 10 

1,000 15 

1.200 22 

NOTE. — Turns  counted  from  the  outside  turn  inward. 

RECEIVING  SET,  TYPE  C 

In  the  earlier  sets,  types  A  and  B,  the  two  circuits  were  magneti- 
cally coupled,  that  is,  the  current  in  the  primary  (open  or  antenna) 
circuit  induced  currents  in  the  secondary  (closed  detector)  circuit 
by  means  of  magnetic  lines  which  passed  from  the  primary  coil 
through  the  turns  of  the  secondary  coil.  In  the  present  set  the  two 
circuits  are  statically  coupled ;  that  is,  the  current  in  the  primary 
circuit  induces  current  in  the  secondary  circuit  by  means  of  static 
lines  in  two  coupling  condensers  connected  in  the  leads  between  the 
circuits.  The  transfer  of  the  energy  from  the  primary  to  the  second- 
ary circuit  for  the  operation  of  the  detector  and  telephones  is  as 
efficient  in  this  type  of  connection  as  in  the  other.  By  choice  of  suit- 
able values  of  the  coupling  condensers  no  movement  of  the  coils  or 
changes  in  coupling  is  necessary  for  the  reception  of  any  wave 
lengths  within  the  range  of  the  set,  as  is  the  case  in  the  former 
sets.  This  reduces  the  number  of  adjustments  for  tuning  from  4  to 
3,  and  at  the  same  time  the  set  is  much  more  rugged,  as  there  are 


424 


MILITARY  SIGNAL  CORPS  MANUAL 


RADIO  APPARATUS  425 

no  moving  parts.  The  values  of  the  coupling  condenser  have  also 
been  so  chosen  as  to  make  the  set  much  more  selective  than  the 
others;  that  is,  it  can  receive  signals  from  a  station  on  one  wave 
length  and  cut  out  signals  from  another  station  on  a  different  wave 
length  more  completely  than  before.  In  addition  to  the  above  ad- 
vantages, the  set  as  a  whole  has  been  found  to  be  more  efficient 
than  the  previous  types. 

The  type  C  receiving  set  consists  of  two  statically  coupled  cir- 
cuits, high-resistance  telephones,  stopping  condenser,  fine  wire- 
galena  detector,  switch  for  short  and  long  wave  lengths,  three  dial 
switches  for  tuning,  etc.  The  circuits  are  shown  diagrammatically 
in  Figure  8. 

The  primary  circuit  consists  of:  (1)  The  antenna,  which  when 
the  control  switch  in  the  cover  of  the  chest  is  thrown  to  the  "Re- 
ceive" position,  is  connected  by  a  double  plug  with  flexible  wires  to 
the  binding  post  on  the  set  marked  "A";  (2)  two  primary  coils  in 
series,  one  large  and  the  other  small,  the  number  of  turns  in  both  of 
which  is  variable  by  means  of  two  dial  switches  marked  "Primary." 
On  each  coil  there  are  contacts,  0  to  24,  for  tuning  to  different  wave 
lengths,  the  dial  nearest  to  the  binding  post  "A"  being  connected  to 
the  large  primary  for  large  changes  in  wave  length  and  the  other  to 
the  small  one  for  small  changes  and  fine  tuning;  (3)  counterpoise 
which  is  connected  to  the  binding  post  marked  "C"  through  the 
double  plug  and  control  switch.  There  is  no  series  condenser  in  the 
antenna  circuit  for  the  reception  of  wave  lengths  shorter  than  the 
fundamental  wave  length  of  the  antenna,  as  in  types  A  and  B,  as  it 
has  been  found  not  to  be  generally  useful. 

When  comparatively  short  wave  lengths  are  to  be  received,  as 
from  300  to  700  meters,  the  double-pole  double-throw  switch  on  top 
of  the  set  should  be  thrown  to  the  position  marked  "Short."  This 
makes  no  changes  in  the  primary  circuit,  but  connects  into  circuit 
(1)  the  secondary  coil  with  the  dial  switch  marked  ^'Secondary," 
with  contacts  0  to  24  for  tuning  to  different  wave  lengths ;  (2) 
detector  and  telephones. 

Short  wave  signals  should  be  picked  up  by  adjustments  of  the 
large  primary  and  the  secondary  dials  and  fine  adjustments  made 
later  on  the  small  primary  dial. 

When  longer  wave  lengths  are  to  be  received,  as  from  500  to 
2,400  meters,  the  D-P  D-T  switch  should  be  thrown  to  the  "Long" 
position.  This  makes  no  changes  in  the  primary  circuit,  but  dis- 
connects the  secondary  coil,  which  in  this  set  is  most  useful  only  at 
•short  wave  lengths,  and  connects  the  circuits  as  shown  in  the  second 
print.  As  the  secondary  coil  is  not  in  circuit,  only  the  two  primary 
dials  are  effective  in  tuning. 


426 


MILITARY  SIGNAL  CORPS  MANUAL 


V 


Jo 
So 

O  v""""^-^- 

Is 

&$ 


I 


6gL 

STQ*- 


F/xed 

coupling 

condensers 


^Ground 


w 


100       Ztefec&r 


Telephone  cond. 


&  (& 

Te/epnor?& 


, 
Antenna 


LONG  WAVE  LENGTHS 
500  TO  1500  METERS 


coupling 
condensers 

—\\ — 


Detector 


FIG.    8.— CIRCUIT    DIAGRAM,    TYPE    C,    RECEIVING    SET 


RADIO  APPARATUS  427 

Long  wave  signals  should  be  picked  up  only  by  adjustment  of  the 
large  primary  dial  and  fine  adjustments  made  later  only  on  the 
small  primary  dial. 

RECEIVING  SET,  TYPE  D 

This  set  is  practically  the  duplicate  of  the  type  C,  except  that 
the  number  of  studs  in  the  three  dials  has  been  increased  so  as  to 
give  finer  tuning. 

TRACTOR  SETS 

The  Signal  Corps  has  designed  and  buflt  two  sizes  of  automobile 
radio  sets,  or  tractor  sets,  as  they  are  called — (a)  a  "divisional" 
tractor  of  1  k.  w.  size;  (&)  an  "Army"  tractor  of  2  k.  w.  size. 

The  1  k.  w.  set,  complete  with  supplies  and  detachment  of  seven 
men,  weighs  about  6,700  pounds,  and  on  an  average  road  is  capable 
of  making  a  speed  of  from  20  to  25  miles  per  hour.  It  carries  a 
60-foot  sectional  mast,  which  can  be  raised  in  a  few  minutes  by 
means  of  guides  on  the  roof  of  the  tractor.  The  antenna  is  of  the 
umbrella  type,  with  16  radiating  wires  each  75  feet  long.  The 
counterpoise  is  likewise  of  the  umbrella  type,  laid  on  the  ground 
with  8  wires,  each  75  feet  long.  The  transmitting  set  is  of  the 
quenched  spark  type,  with  inductively  coupled  circuits  adjusted  to 
radiate  waves  of  600,  800,  1,000,  and  1,200  meters.  The  re- 
ceiving set  is  of  the  statically  coupled  type  similar  to  that  in  use  in 
the  1915  radio  pack  sets,  but  of  larger  size  and  capable  of  reception 
of  much  longer  wave  lengths. 

The  2  k.  w.  set,  complete  with  supplies  and  detachment  of  eight 
men,  weighs  about  9,000  pounds,  and  on  an  average  road  is  capable 
of  making  a  speed  of  at  least  15  miles  per  hour.  It  carries  an  80- 
foot  sectional  mast,  which  is  raised  in  a  manner  similar  to  that  in 
the  1  k.  w.  set.  The  transmitting  and  receiving  sets  are  likewise 
similar  to  those  in  the  previous  set,  but  capable  of  using  much  longer 
wave  lengths. 


VISUAL  SIGNALING  EQUIPMENT 

THE    WAND 

The  wand  is  a  stick  of  light  wood  about  18  inches  long  and 
one-half  inch  in  diameter.  It  is  held  loosely  between  the  thumb 
and  forefinger  and  waved  rapidly  to  the  right  or  left  to  indicate 
the  elements  of  the  alphabet.  It  is  used  for  practice  purposes 
and  the  signals  made  by  it  are  only  intended  to  be  read  at  very 
short  distances. 

FLAG  KITS,  GENERAL  SERVICE  AND  SEMAPHORE 

Five  kinds  of  flag  kits  are  issued  by  the  Signal  Corps :  The 
standard  2-foot  kit,  the  infantry  2-foot  kit,  and  the  standard 
4-foot  kit,  for  use  with  the  General  Service  Code,  and  two  types 
of  semaphore  flag  kits,  one  standard  and  the  other  of  a  pattern 
temporarily  in  service  in  the  field  and  coast  artillery,  both  for 
use  with  the  Two-arm  Semaphore  Code. 

The  2-foot  kit. — The  standard  2-foot  kit  consists  of  one 
white  and  one  red  signal  flag,  one  3-jointed  staff,  and  a  suitable 
carrying  case  to  contain  the  outfit.  The  white  flag  is  made  of 
white  galatea  2  feet  square,  with  an  8-inch  turkey-red  center. 
The  red  flag  is  of  similar  size  and  material,  the  only  difference 
being  an  alternation  of  colors  in  the  body  and  center.  The 
means  of  attachment  to  the  staff  consists  of  a  loop  at  the  cen- 
ter and  two  ends  of  white  tape  at  each  edge  of  the  back  of  the 
flag  body.  The  staff  is  made  of  hickory  in  three  joints,  each  23 
inches  long,  and  is  assembled  by  means  of  brass  screw  ferrules. 
Brass  eyes  are  provided  on  the  first  and  second  joints  to  receive 
the  tape  ends  at  the  edge  of  the  flag.  The  olive  drab  carrying 
case  is  of  convenient  size  and  shape  to  contain  two  flags  and 
staffs  complete,  and  is  bound  with  leather  and  fitted  with  a 
shoulder  strap. 

The  combination  infantry,  2-foot  kit. — The  combination, 
infantry,  2-foot  kit  is  essentially  the  same  as  the  combination, 
standard,  2-foot  kit,  except  that  1  infantry  flag,  as  prescribed 
by  Infantry  Drill  Regulations,  is  substituted  for  the  two  2-foot 
red  and  white  flags  described. 

The  standard  4-foot  kit. — The  standard  4-foot  kit  consists 
of  1  case,  canvas;  1  staff,  3-joint,  and  1  flag,  red.  white  square; 

428 


riSl'AL   SIGXAL1XG   EQUIPMENT  429 

and  1  flag,  white,  red  square.  The  flags  are  3  feet  9  inches 
square,  with  12-inch  centers,  and  the  staffs  are  considerably 
heavier  than  those  of  the  standard  2-foot  kit,  each  joint  being 
36  inches  long.  The  4-foot  kit  is  the  standard  field  flag  kit,  and 

SIGNAL  CORPS  TWO  FOOT  FLAGS 


SIGNAL  CORPS  FOUR  FOOT  FLAGS 


SEMAPHORE  HAND  FLAGS 


the  range  at  which  signals  can  be  exchanged  with  it  depends  on  a 
variety  of  factors,  such  as  conditions  of  the  weather,  the  location  of 
stations,  the  proficiency  of  signalmen,  etc.  The  speed  for  con- 


430  MILITARY  SIGNAL  CORPS  MANUAL 

tinuous    signaling    is    seldom    greater    than    five  to  six  words  per 
minute. 

Powers  and  limitations  of  flag  signaling. — The  advantages 
which  may  be  claimed  for  this  method  of  signaling  are  port- 
ability of  apparatus,  adaptability  to  varied  weather  conditions, 
and  great  rapidity  of  station  establishment.  The  disadvan- 
tages are  the  lack  of  celerity  of  the  signals,  their  impenetra- 
bility to  dust  or  smoke,  and  the  comparatively  short  ranges 
at  which  they  can  be  read.  These  ranges  vary  with  the  back- 
ground, light,  vision,  and  power  of  glasses  if  used. 

Care  of  flag  material. — Signal  flags  should  be  examined  at 
the  close  of  drill  or  practice  and  repairs  made  to  any  rents  or 
loose  ties  discovered.  Flags,  when  soiled,  should  be  thoroughly 
washed  and  dried  in  the  sun.  Signals  made  by  clean  flags  are 
much  more  easily  read  than  those  made  by  dirty  ones.  Staffs 
should  be  handled  with  care,  especially  when  jointing  or 
unjointing.  Care  should  be  taken  not  to  bruise  the  ends  of 
the  brass  ferrules.  Ferrules  fitting  together  so  loosely  as  to 
permit  separation  of  the  joints  in  signaling  must  not  be  ham- 
mered or  jammed,  but  should  be  tightened  by  wrapping  one  or 
more  thicknesses  of  thin  paper  around  the  one  which  is 
inserted  in  the  other.  If  a  ferrule  becomes  loose  on  a  staff 
it  should  be  tightened  without  delay. 


THE   HELIOGRAPH 

The  heliograph  is  an  instrument  designed  for  the  purpose  of 

transmitting  signals  by  means  of  the  sun's  rays. 

Description.— The  service  heliograph  equipment  of  the  Signal 
Corps  consists  of: 

A  sole-leather  pouch  with  shoulder  strap  containing — 

1  sun   mirror.         7  T 

1  station  mirror.    {  Inclosed  m  a  wooden  box' 

1  shutter,  1  sighting  rod,  1  screw  driver. 

A  small  pouch,  sliding  by  2  loops  upon  the  strap  of  the  larger 
pouch,  containing  1  mirror  bar. 

A  skeleton  leather  case  containing  2  tripods. 
The  mirrors  are  of  plate  glass,  each  4^-inch  square,  supported 
by  sheet  brass  and  cardboard  backings,  and  mounted  in  brass  re- 
taining frame  The  sun  mirror  has  a  paper  disk  covering  the  un- 
silvered  spot  in  its  center.  The  mirror  frames  are  carried  by  brass 
supports  provided  at  the  bases  with  conical  projections  accurately 
turned  to  fit  the  sockets  of  the  mirror  bar  and  grooved  at  the  ends 
to  receive  the  clamping  spring.  Each  support  is  fitted  with  a  tangent 
screw  and  worm-wheel  attachment  functioned  to  control  the  motion 
of  the  mirror-frame  about  its  horizontal  axis. 

The  mirror  bar  is  a  bronze  casting  provided  at  the  center  with 
a  clamp  threaded  to  fit  the  screw  of  the  tripod.  By  releasing  the 
clamp  the  bar  may  be  moved  independently  of  the  screw  and  ad- 
justed to  any  desired  position.  Conical  sockets  for  the  reception 
of  the  mirror  supports  are  provided  at  the  ends  of  the  mirror  bar. 
These  sockets  work  freely  in  the  bar  and,  being  actuated  by  a 
tangent  screw  and  worm  wheel,  serve  to  regulate  the  motion  of  the 
mirror  frame  about  its  vertical  axis.  Clamp  springs,  for  engaging 
and  securing  the  ends  of  the  mirror-frame  supports,  are  attached 
at  each  end  of  the  bar. 

The  shutter  is  6%  inches  square,  six  segments  or  leaves  being 
mounted  in  such  a  way  as  to  form  a  shutter.  The  leaves  are  de- 
signed to  turn  through  arcs  of  90  deg.  on  horizontal  axes,  unanimity 
of  movement  being  secured  by  connections  made  with  a  common 
crank  bar.  The  crank  bar  is  operated  by  a  key  and  retractile 
spring  which  serve  to  reveal  and  cut  off  the  flash.  A  set  screw  and 
check  nut  at  the  lower  edge  of  the  screen  frame  limits  the  motion 

431 


432  MILITARY  SIGNAL  CORPS  MAXl'JL 

of  the  crank  bar  and  the  opening  of  the  leaves.  A  threaded  base 
support  furnishes  the  means  of  attaching  the  screen  frame  to  the 
tripod. 

The  sighting  rod  is  a  brass  rod  6l/2  inches  long,  carrying  at  the 
upper  end  a  front  sight  and  a  movable  disk.  About  the  rod  is  fitted 
a  movable  bronze  collar,  coned  and  grooved  to  take  the  socket  and 


THE   HELIOGRAPH   ASSEMBLED 

clamping  spring  of  the  mirror  bar.     A  milled-edged  bronze  washer 
serves  to  clamp  the  collar  to  the  rod  at  any  desired  point. 

The  tripods  are  similar  in  all  respects,  the  screw  of  either  thread- 
ing into  the  mirror  bar  or  shutter  frame.     Each  tripod  is  provided 


THE  HELIOGRAPH  433 

with  a  hook  at  the  base  of  the  head,  allowing  the  suspension  of  a 
weight  when  great  stability  is  required. 

Assembling. — There  are  two  ways  of  assembling  the  heliograph, 
and  the  position  of  the  sun  is  the  guide  in  determining  which  of 
the  two  should,,  in  any  given  case,  be  employed.  When  the  sun 
is  in  front  of  the  operator  (that  is,  in  front  of  a  plane  through  his 
position  at  right  angles  to  the  line  joining  the  stations)  the  sun 
mirror  only  is  required ;  with  the  sun  in  rear  of  this  plane  both 
mirrors  should  be  used.  With  one  mirror  the  rays  of  the  sun  are 
reflected  directly  from  the  sun  mirror  to  the  distant  station ;  with 
two  mirrors,  the  rays  are  reflected  from  the  sun  mirror  to  the  sta- 
tion mirror,  and  thence  to  the  distant  station. 

With  one  mirror :  Firmly  set  one  of  the  tripods  upon  the  ground ; 
attach  the  mirror  bar  to  the  tripod;  insert  and  clamp  in  the  sockets 
of  the  sun  mirror  and  sighting  rod,  the  latter  having  the  disk  turned 
down.  At  a  distance  of  about  6  inches,  sight  through  the  center 
of  the  unsilvered  spot  in  the  mirror  and  turn  the  mirror  bar,  rais- 
ing or  lowering  the  sighting  rod  until  the  center  of  the  mirror,  the 
extreme  point  of  the  sighting  rod,  and  the  distant  station  are  ac- 
curately in  line.  Firmly  clamp  the  mirror  bar  to  the  tripod,  taking 
care  not  to  disturb  the  alignment,  and  turn  up  the  disk  of  the  sight- 
ing rod.  The  mirror  is  then  moved  by  means  of  the  tangent  screws 
until  the  "shadow  spot"  falls  upon  the  paper  disk  in  the  sighting 
rod,  after  which  the  flash  will  be  visible  at  the  distant  station. 
The  "shadow  spot"  is  readily  found  by  holding  a  sheet  of  paper 
or  the  hand  about  6  inches  in  front  of  the  mirror,  and  should  be 
constantly  kept  in  view  until  located  upon  the  disk.  The  shutter 
is  attached  to  a  tripod  and  established  close  to,  and  in  front  of, 
the  sighting  disk  in  such  a  way  as  to  intercept  the  flash. 

With  two  mirrors'.  Firmly  set  one  of  the  tripods  on  the  ground; 
clamp  the  mirror  bar  diagonally  across  the  line  of  vision  to  the 
distant  station;  clamp  the  sun  mirror  facing  the  sun  to  one  end  of 
the  mirror  bar  and  the  station  mirror  facing  the  distant  station. 
Stooping  down,  the  head  near  and  in  rear  of  the  station  mirror, 
turn  the  sun  mirror  by  means  of  its  tangent  screws  until  the  whole 
of  the  station  mirror  is  seen  reflected  in  the  sun  mirror  and  the 
unsilvered  spot  and  the  reflection  of  the  paper  disk  accurately 
cover  each  other.  Still  looking  into  the  sun  mirror,  adjust  the 
station  mirror  by  means  of  the  tangent  screws  until  the  reflection 
of  the  distant  station  is  brought  exactly  in  line  with  the  top  of 
the  reflection  of  the  disk  and  the  top  of  the  unsilvered  spot  of  the 
sun  mirror ;  after  this  the  station  mirror  must  not  be  touched.  Now 
step  behind  the  sun  mirror  and  -adjust  it  by  means  of  the  tangent 
screws  so  that  the  "shadow  spot"  falls  upon  the  center  of  the  paper 
disk  on  the  station  mirror.  The  flash  will  then  be  visible  at  the 


434  MILITARY  SIGNAL  CORPS  MANUAL 

distant  station.     The  shutter  and  its  tripod  are  established  as  de- 
scribed in  the  single  mirror  assembling. 

Alternate  method  with  two  mirrors. — Clamp  the  mirror  bar  diag- 
onally across  the  line  of  vision  to  the  distant  station,  with  the 
sun  mirror  and  the  station  mirror  approximately  facing  the  sun  and 
distant  station,  respectively. 

Look  through  small  hole  in  sun  mirror  and  turn  the  station 
mirror  on  its  vertical  and  horizontal  axes  .until  the  paper  disk  or.  the 
station  mirror  accurately  covers  the  distant  station. 

Standing  behind  sun  mirror,  turn  it  on  its  horizontal  and  vertical 
axes  by  means  of  the  tangent-screw  attachments  until  the  shadow 
spot  falls  upon  the  paper  disk  on  station  mirror. 

Adjustment. — Perfect  adjustment  is  maintained  only  by  keep- 
ing the  "shadow  spot"  uninterruptedly  in  the  center  of  the  paper 
disk,  and  as  this  "spot"  continually  changes  its  position  with  the 
apparent  movement  of  the  sun,  one  signalman  should  be  in  constant 
attendance  on  the  tangent  screws  of  the  sun  mirror.  Movement 
imparted  by  these  screws  to  the  mirror  does  not  disturb  the  align- 
ment, as  its  center  (the  unsilvered  spot)  is  at  the  intersection  of 
the  axes  of  revolution.  Extra  care  bestowed  upon  preliminary  ad- 
justment is  repaid  by  increased  brilliancy  of  flash.  With  the  align- 
ment absolutely  assured  and  the  "shadow  spot"  at  the  center  of 
the  disk,  the  axis  of  the  cone  of  reflected  rays  is  coincident  with 
the  line  of  sight  and  the  distant  station  receives  the  greatest  inten- 
sity of  light.  Remember  the  distant  observer  is  unquestionably 
the  better  judge  as  to  the  character  of  the  flash  received ;  and  if, 
therefore,  adjustment  is  called  for  when  the  "shadow  spot"  is  at  the 
center  of  the  disk,  the  alignment  is  probably  at  fault  and  should  be 
looked  after  at  once.  In  setting  up  the  tripods  always  see  that  the 
legs  have  a  sufficient  spread  to  give  a  secure  base,  and  on  yielding 
soil  press  firmly  into  the  ground.  Keep  the  head  of  the  tripod  as 
nearly  level  as  possible  and  in  high  wind  ballast  by  hanging  a  sub- 
stantial weight  to  the  hook.  See  that  the  shutter  completely  ob- 
scures the  flash ;  also  that  the  flash  passes  entire  when  the  shutter 
is  opened.  This  feature  of  the  adjustment  is  partially  regulated 
by  the  set  screw  attached  to  the  shutter  frame.  The  retractile 
spring  should  sharply  return  all  the  leaves  of  the  shutter  to  their 
normal  positions  when  the  key  is  released.  Failure  to  respond 
promptly  is  obviated  by  strengthening  or  replacing  the  spring. 

Operation. — It  is  of  the  utmost  importance  that  uniformity  in 
mechanical  movement  of  the  shutter  be  cultivated,  as  lack  of  rhythm 
in  the  signals  of  the  sender  entails  "breaks"  and  delay  on  the  part 
of  the  receiver  Dark  backgrounds  should,  when  practicable,  be 
selected  for  heliograph  stations,  as  the  signals  can  be  most  easily 
distinguished  against  them. 


THE  HELIOGRAPH  435 

To  find  a  distant  station,  its  position  being  unknown,  reverse 
the  catch  holding  the  station  mirror  and  with  the  hand  turn  the 
mirror  very  slowly  at  the  horizon  over  the  full  azimuth  distance 
in  which  the  distant  station  may  possibly  lie.  This  should  be 
repeated  not  less  than  twice,  after  which,  within  a  reasonable  time, 
there  being  no  response,  the  mirror  will  be  directed  upon  a  point 
nearer  the  home  station  and  the  same  process  repeated.  With 
care  and  intelligence  it  is  quite  probable  that,  a  station  being 
within  range  and  watching  for  signals  from  a  distant  station  with 
which  it  may  be  desired  to  exchange  messages,  this  method  will 
rarely  fail  to  find  the  sought-for  station. 

The  exact  direction  of  either  station  searching  for  the  other 
being  unknown,  that  station  which  first  perceives  that  it  is  being 
called  will  adjust  its  flash  upon  the  distant  station  to  enable  it 
when  this  light  is  observed  to  make  proper  adjustments.  If  the 
position  of  each  station  is  known  to  the  other,  the  station  first 
ready  for  signaling  will  direct  a  steady  flash  upon  the  distant  sta- 
tion to  enable  the  latter  to  see  not  only  that  the  first  station  is 
ready  for  work,  but  to  enable  the  distant  station  to  adjust  its  flash 
upon  the  first  station. 

Smoked  or  colored  glasses  are  issued  for  the  purpose  of  re- 
lieving the  s*  ain  on  the  eyes  produced  by  reading  heliograph 
signals. 

Care  of  apparatus. — Minor  parts  of  the  instrument  should 
be  dismounted  only  to  effect  repairs.  Steel  parts  should  be  kept 
oiled  and  free  from  rust.  Tangent  screws  and  bearings  should  be 
frequently  inspected  for  dust  or  grit.  Mirrors  should  invariably  be 
wiped  clean  before  using.  In  case  of  accident  to  the  sun  mirror, 
the  station  mirro-  can  be  made  available  for  substitution  therefor 
by  removing  the  paper  disk.  If  the  tripod  legs  become  loose  at  the 
head  joints,  tighten  the  assembling  screws  with  the  screw  driver. 

Powers  and  limitations  of  the  heliograph. — Portability, 
great  range,  comparative  rapidity  of  operation,  and  the  invisibility 
of  the  signals,  except  to  observers  located  approximately  on  a  right 
line  joining  the  stations  between  which  communication  is  had, 
are  some  of  the  advantages  derived  from  using  the  heliograph  in 
visual  signaling. 

The  principal  disadvantage  results  from  the  entire  dependence 
of  the  instrument  upon  the  presence  of  sunlight.  The  normal  work- 
ing range  of  the  heliograph  is  about  30  miles,  though  instances  of 
its  having  attained  ranges  many  times  greater  than  this  are  of 
record.  The  heliograph  can  be  depended  upon  to  transmit  from 
5  to  12  words  per  minute. 


THE   ACETYLENE  LANTERN 

The  signal  lantern  is  an  instrument  designed  for  the  purpose 
of  transmitting  signals  by  means  of  intermittent  flashes  of  artificial 
light.  It  is  the  standard  night  visual  signaling  equipment  furnished 
by  the  Signal  Corps  and  depends  for  its  illumination  upon  the  com- 
bustion of  acetylene  gas. 

Acetylene. — Acetylene  is  a  pure  hydrocarbon  gas,  producible  in 
various  ways,  the  commoner  of  which  are :  (a)  By  dropping  cal- 
cium carbide  into  water;  (&)  by  dropping  water  upon  calcium  car- 
bide. This  gas  gives,  when  burning,  high  penetrative  power,  and 
was  first  described  by  Mr.  Edmund  Davy,  professor  of  chemistry 
to  the  Royal  Dublin  Society,  in  1836. 

Calcium  carbide. — In  the  manufacture  of  calcium  carbide  for 
commercial  purposes  the  best  quality  of  coke  and  quicklime  are 
used.  These  two  substances  are  powdered  thoroughly,  mixed  in 
proper  proportions,  and  then  placed  in  an  electrical  furnace.  Under 
the  action  of  the  intense  heat  (5,500  deg.  F.)  these  two  refractory 
substances  unite  and  form  calcium  carbide.  Calcium  carbide  is  of 
a  grayish-white  color,  crystal  in  appearance,  and  is  nonexplosive 
and  noncombustible,  being,  except  for  its  affinity  for  water,  an  abso- 
lutely inert  substance. 

When  calcium  carbide  is  brought  in  contact  with  water  the  fol- 
lowing occurs : 

As  is  known,  the  principal  components  of  water  are  oxygen 
and  hydrogen,  and  calcium  carbide  is  calcium  and  carbon.  When 
brought  in  contact,  the  oxygen  in  the  water  decomposes  the  cal- 
cium in  the  carbide,  and  in  this  decomposition  the  hydrogen  in  the 
water  is  liberated  and  unites  with  the  carbon  of  the  carbide, 
forming  a  hydrocarbon  gas,  which  is  acetylene.  It  gives  a  pure  white 
light  of  intense  brilliancy  and  high  candlepower.  The  spectrum 
analysis  of  acetylene  shows  that  it  is  almost  identical  with  sunlight, 
and  in  consequence  delicate  shades  of  color  appear  according  to 
their  true  value  as  under  the  light  of  the  sun,  consequently  it 
penetrates  fog  to  a  greater  distance  than  other  lights.  Acetylene 
is  like  other  gases — explosive  when  mixed  with  air  in  proper  pro- 
portions, confined,  and  ignited— and  the  same  precautions  should 

436 


THE  ACETYLENE  LANTERN  437 

therefore  be  taken  in  its  use  as  would  be  in  the  handling  of  coal  or 
water  gas,  gasoline  vapor,  etc.  As  acetylene  is  very  rich  in  carbon, 
it  will  not  burn  in  its  pure  state  without  smoking.  To  avoid  this, 
burners  have  been  constructed  so  that  the  gas  is  mixed  with  the 
proper  proportion  of  air  at  the  burner  tip,  to  insure  perfect  com- 
bustion. The  burners  for  acetylene  are  different  from  those  for 
other  gaseo.  In  order  to  get  a  flat  flame,  the  gas  is  brought  through 
two  perfectly  round  holes  at  an  angle  which  causes  the  two  flames 
to  impinge  upon  each  other  and  thus  form  a  flat  flame. 

Method  of  gas  generation. — The  method  employed  for  pro- 
ducing acetylene  in  the  signal  lantern  is  by  bringing  water  into 
contact  with  the  calcium  carbide.  The  disadvantage  of  this  method 
is  that  when  the  water  is  not  in  excess  and  does  not  entirely  sur- 
round and  touch  each  piece  of  carbide  the  heat  of  generation  will 
so  change  the  chemical  properties  of  the  gas  that  combustion  at  the 
burners  is  not  satisfactory. 

This  change  is  technically  known  as  "polymerization,"  or  the 
breaking  up  of  acetylene  into  other  hydrocarbons,  such  as  vapors 
of  benzine,  benzole,  etc.  These  form  a  tarry  substance  which  is 
apt  to  condense  at  the  burner  tip  and  clog  the  openings.  Also 
they  deposit  carbon  on  the  burners,  as  they  require  more  air  for 
perfect  combustion  than  does  pure  acetylene.  Another  disad- 
vantage of  this  system  is  that  after  the  carbide  and  water  are  in 
contact,  generation  of  gas  will  continue  until  all  the  water  is 
absorbed.  Where,  however,  portability  of  the  generating  appara- 
tus is  desired  and  resort  to  this  method  is  necessary,  the  objections 
are  not  important,  if  the  apparatus  is  well  constructed  and  care  is 
taken  in  its  use. 

Description. — This  equipment  consists  of  a  signal  lantern  with 
cartridge  generator  attached.  The  lantern  is  fitted  with  a 
special  aplanatic  lens  mirror,  5  inches  in  diameter  and  about  3 
inches  focus.  The  lantern  is  packed  complete  in  a  wooden  case 
with  shoulder  straps  and  the  following  extra  parts  are  included, 
each  part  having  its  own  receptacle  in  the  case :  2  burners,  1  cover 
glass,  3  cartridges  of  calcium  carbide  of  5  ounces  each,  1  pair  of  gas 
pliers,  1  tube  white  lead,  1  extra  filter  bag,  1  screw  driver. 

The  lantern  is  made  of  brass,  all  parts  of  which  are  riveted. 
The  burner  is  of  the  double  tip  form.  The  lantern  is  fitted  with  a 
hood  to  provide  proper  ventilation  and  at  the  same  time  to  prevent 
the  flickering  of  the  light  by  the  wind.  The  front  door  of  the 
lantern  is  hinged  and  fastens  with  a  spring  clasp;  it  is  so  arranged 
that  it  can  be  entirely  removed  if  necessary.  The  cover  glass  is 
made  in  three  sections  and  is  not  affected  by  the  expansion  and 
contraction  of  the  metal  due  to  changes  in  temperature.  The  glass 
is  fastened  by  the  aid  of  a  spring  wire,  so  that  it  can  be  readily  re- 
moved if  it  is  necessary  to  replace  a  broken  section.  In<the  base  of 


438 


MILITARY  SIGNAL  CORPS  MANUAL 


5', 


LANTERN  WITH  GENERATOR 
ATTACHED 


SIGNAL  LANTERN- 
ASSEMBLED 


the  lantern  is  a  key  and  the  ad- 
justment for  regulating  the  height 
of  the  flame.  The  key  is  so  ar- 
ranged that  when  not  depressed  but 
little  gas  is  admitted  through  to  the 
burner,  which  gives  a  bright  flash.  At 
the  back  of  the  lantern  there  is  an  ad- 
justable handle,  so  that  the  equip- 
ment can  be  used  as  a  hand  lantern 
if  desired.  This  form  of  lantern 
can  be  used  with  the  regular  helio- 
graph tripod,  the  generator  being 
either  attached  to  the  back  of  the 
lantern  or  suspended,  as  shown  in 
the  photograph.  When  practicable 
it  is  better  to  attach  the  generator 
to  the  lantern,  as  shown  in  the 
smaller  view.  The  candlepower  of 
this  lantern  is  about  1,900. 

The  generator  used  is  known  as 
"the  cartridge  generator,"  and  while 
constructed  on  the  water-feed  prin- 
ciple, the  disadvantages  incident  to 
this  method  are  eliminated  as  far 
as  possible.  It  is  constructed  of 
brass  and  has  a  removable  top.  At- 
tached to  the  inside  of  the  top  is  a 
flexible  frame  with  a  spring  latch, 
the  spring  latch  being  hinged.  At 
the  top  of  the  frame  is  a  tube  or 
cylinder,  the  bottom  of  which  is 
conical  in  shape  and  covered  by  a 
rubber  plug.  At  the  bottom  of  the 
frame  is  a  hollow  tube,  which  is  the 
water  inlet.  The  cartridge  proper 
consists  of  a  tin  cylinder  having  an 
opening  at  either  end  a  small  cylinder 
of  wire  mesh  extends  from  and 
connects  these  openings.  The  car- 
bide lays  around  this  mesh  on  the 
inside  of  the  cartridge.  The  rubber 
plug  before  mentioned  fits  into  the 
upper  opening  and  the  water  tube 
into  the  lower  opening.  Inside  the 
tube,  at  the  top  of  the  frame,  is  a 


THE  ACETYLENE  LANTERN 


439 


filter,  the  function  of  which  is  to  remove  the  dust  and  moisture 
from  the  gas.  The  outlet  from  this  chamber  is  by  a  brass  bent 
tube  having  a  stopcock  attached  thereto. 

The  drawing  gives  a  sectional  view  of  the  generator  with  the  cart- 
ridge in  place.  D  F  G  H  represent  the  valve  frame  and  /  the 
cartridge  attached.  The  reservoir  A  is  filled  with  water,  and 
when  the  frame  is  immersed,  with  the  valve  R  closed,  the  air 
contained  in  the  cartridge  and  tubing  can  not  escape,  the  water  seal 
preventing,  while  the  confined  air  prevents  the  water  from  rising 

in  the  tube  N.  When 
the  valve  at  R  is  opened 
and  the  air  is  allowed 
to  escape,  part  of  the 
water  from  the  reser- 
voir rises  into  the  tube 
N  and  then  out  through 
the  small  hole  O  to  the 
carbide.  Gas  is  imme- 
diately generated,  the 
pressure  of  which  pre- 
vents further  ingress 
of  the  water  from  the 
tube  N,  and  the  gener- 
ation of  gas  is  sus- 
pended. 

As  the  gas  passes 
out  through  the  valve 
at  R  the  pressure  de- 
creases, permitting  the 
water  to  again  rise  in 
the  tube  and  flow 
through  O.  Gas  is  again  generated,  which  at  once  ex- 
erts its  pressure  and  cuts  off  the  supply  of  water.  This 
is  the  automatic  action  by  which  water  is  brought  in  contact  with 
the  calcium  carbide.  Thus  it  will  be  observed  that  the  use  or 
escape  of  the  gas  regulates  the  generation  by  the  simple  device 
of  the  rise  and  fall  of  a  water  column.  There  is  a  cap  M  screwed 
over  the  tube  TV.  This  is  used  to  deflect  the  course  of  the  water 
downward,  so  that  the  carbide  in  the  lower  part  of  the  cartridge 
is  first  attacked.  There  is  a  needle  inside  of  cap  M,  which  can  be 
used  for  cleaning  the  hole  0.  When  the  gas  is  generated  it  passes 
through  the  filter  D  on  its  way  to  the  burner  through  R.  This 
filter  consists  of  a  tube  loosely  packed  with  ordinary  nonabsorb- 
ent  cotton,  which  should  never  cover  the  escape  pipe  leading  to 
the  valve  R.  In  passing  through  this  cotton  filter  moisture  and 


SIGNAL   LANTERN   GENERATOR 


440  MILITARY  SIGNAL  CORPS  MANUAL 

dust  are  removed  from  the  gas.  In  the  latest  model  a  felt  filter 
is  used  instead  of  cotton. 

The  escape  pipe  F  provides  a  means  for  the  escape  of  gas 
generated  and  not  used,  or  generated  more  rapidly  than  consumed. 
Should  an  excess  be  generated,  it  passes  down  through  the  tube  F ' , 
and,  finding  its  way  through  some  small  holes  in  the  bottom  of 
this  tube,  escapes  through  the  water  seal  and  the  opening  at  C. 
It  will  be  noted  that  if  escaping  gas  at  C  should  become  acci- 
dentally lighted,  the  flame  can  not  strike  back  into  the  filter  and 
cartridge  because  of  the  water  seal.  The  principal  things  to  ob- 
serve in  the  operation  of  this  generator  are  the  following: 

(1)  To  see  that  the  rubber  plugs  fit  tightly  into  the  openings 
of  the  cartridge. 

(2)  That  the  tube  N,  the  cap  M,  and   water  hole   O  are  not 
stopped  up. 

(3)  That   the  cotton  in   the   filter   is  changed   frequently. 

(4)  That  the  stopcock  R  is  closed  before  inserting  the  frame  in 
the  water.     If  this  latter  instruction  is  not  complied  with,  it  can 
be  readily  seen  that  the  water  will  have  free  access  to  the  carbide 
and  excessive  generation  will  occur. 

When  the  charge  is  exhausted  the  entire  cartridge  is  taken 
out  and  thrown  away.  This  eliminates  the  handling  of  carbide 
and  the  disagreeable  task  of  cleaning  out  the  residuum  after  the 
gas  has  been  extracted. 

Connection  is  made  from  the  stopcock  R  to  the  hose  con- 
nection on  the  lantern  proper,  and  this  is  the  passageway  of  the 
gas  from  the  generator  to  the  burner.  As  soon  as  the  stopcock  is 
opened  the  water  rises  through  the  tube  and  flows  to  the  carbide. 
The  advantage  of  the  cartridge  being  submerged  in  the  water  is 
to  reduce  and  absorb  as  much  of  the  heat  liberated  by  generation 
as  is  possible. 

Powers  and  limitations   of  the  acetylene  signal  lantern. — As 

conditions  are  usually  more  uniform  at  night  than  in  the  daytime, 
the  signal  lantern  is  probably  with  the  exception  of  the  search- 
light the  most  reliable  of  all  means  of  visual  signaling.  The  advan- 
tages of  this  apparatus  are  its  portability,  speed  of  operation,  and 
comparatively  great  range.  The  principal  disadvantages  are  due 
to  the  interference  caused  by  rain,  fog,  and  moonlight.  The 
speed  attainable  with  the  lantern  is  about  the  same  as  that  at- 
tainable with  the  heliograph.  In  emergency,  and  for  distances 
not  exceeding  ^  to  &  mile,  the  lantern  can,  on  dark  or  cloudy 
days,  be  employed  for  day  signaling.  These  lanterns  have  been 
tested  up  to  a  distance  of  10  miles  with  the  naked  eye;  and  under 
favorable  conditions  can  be  used  over  a  range  somewhat  in  ex- 
cess of  this.  With  a  30  power  telescope,  the  flash  can  be  read 
at  30  miles. 


TECHNICAL  EQUIPMENT  OF  PERSONNEL 

The  technical  equipment  for  men  of  a  field  company,  Signal 
Corps,  is  as  follows: 

(a)  Each  enlisted  man  carries  on  the  person  1  electrician's 
knife,  1  pair  of  5-inch  pliers. 

(b)  Chiefs  of  section*  carry,  in  addition  to  (a),  1  field  glass, 
Type  D,  a  wrist  watch,  map  case  and  map,  a  field  message  book, 
a  pencil  and  a  compass. 

(c)  Operators  carry,  in  addition  to  (a) :    Of  wire  sections — 
1  field  buzzer  (when  not  carried  on  the  wire  cart),  1  connector, 
buzzer,  1  ground  rod,  1  wrist  watch,  1  field  message  book,  and 
25  message  envelopes,  2  pencils,  1  small  roll  of  tape,  1  cipher 
disk.    Of  wireless  stations — 1  wrist  watch,  and  also  field  mes- 
sage books,  25  message  envelopes,  2  pencils,  cipher  disk  and 
tape  in  the  pack  chests. 

(d)  Linemen  carry,  in  addition  to  (a),  1  wire  pike,  1  cavalry 
buzzer,  1  connector,  buzzer,  1  ground  rod,  1  carrier  with  buzzer 
wire,  1  small  roll  of  tape.    The  pike  is  not  carried  at  ceremonies 
except  at  mounted  inspection. 

(e)  Messengers  carry,  in  addition  to  (a)  :    Of  wire  sections — 
1  field  message  book,  1  pencil,  1  small  roll  of  tape,  1  box  of  wind 
matches,  and,  when  not  carried  on  the  wire  cart,  a  lantern,  3 
candles,   and   box  of   wind   matches.    Of   wireless   sections — 1 
field  message  book,  1  pencil. 

(f)  Horsebolders  (dismounted:  line  guards)  carry,  in  addi- 
tion to  (a) :  Of  wire  sections — 1  small  roll  of  tape,  and,  when, 
not  carried  on  the  wire  cart,  a  lantern,  3  candles,  and  a  box  of 
wind  matches. 

441 


PART  IV— TRANSMISSION. 


TRANSMISSION    OF    MILITARY    INFORMATION 

Many  as  have  been  the  changes  that  applied  science  has  effected 
in  civilized  life  during  the  past  hundred  years,  no  single  one  has 
been  more  revolutionary,  perhaps,  than  that  which  has  taken 
place  in  the  transmission  of  human  thought.  A  century  ago  the 
great  semaphore  system  of  France  marked  probably  the  farthest 
advance  in  the  world's  telegraphy,  whereas  to-day  we  put  a  girdle 
of  thought  around  the  earth  in  the  twinkling  of  an  eye ;  our  uttered 
words  pass  beyond  the  range  of  sight  or  sound  and  reach  beyond 
the  limit  of  years.  Space  and  time  have  in  this  sense  been  anni- 
hilated. 

That  the  change  has  been  due  to  electricity  is  known  to  us  all ; 
yet  who  stops  to  realize  that  until  the  first  message  of  the  Morse 
telegraph  passed  from  Washington  to  Baltimore  thought  was  con- 
veyed much  as  it  had  been  between  men  since  the  dawn  of  history. 
That  the  influence  of  this  change  has  been  as  extended  in  war  as 
it  has  in  peace  is  perhaps  too  much  to  say,  since  peace  is  long  con- 
struction, war  speedy  destruction ;  but  that  the  value  of  the  change 
is  the  greater  in  war  is  as  sure  as  that  the  need  is  greater.  If  proof 
of  this  value  is  necessary,  we  have  only  to  recall  Shafter's  com- 
munication at  a  critical  moment  with  the  White  House  from  the 
field  at  Santiago  which  the  Signal  Corps  had  placed  by  cable  within 
five  minutes  of  Washington,  or,  more  recently,  the  events  abroad,  of 
which  we  have  but  a  glimmer  of  knowledge,  but  yet  sufficient  evi- 
dence to  show  the  vital,  almost  transcendent,  importance  in  war  of 
the  transmission  of  information,  so  signally  illustrated  in  many 
actions. 

But  in  war,  as  in  peace,  changed  methods  of  intelligence  com- 
munication—with all  that  this  implies— have  been  due  to  many 
agencies;  chemistry  and  the  mechanical  arts  have,  of  themselves, 
done  their  share  in  improvement  and  given  us  aircraft  in  vary- 
ing forms,  the  searchlight,  the  heliograph,  the  acetylene  light,  pyro- 
technics, and  many  other  useful  devices.  But  other  agencies  have 
played  their  part,  and  the  fighting  world  no  longer  moves  only  on 
the  surface  of  land  and  water.  Indeed,  advances  in  the  arts  of 
peace  have  vastly  increased  fighting  power  in  war,  and  the  applica- 

442 


TRANSMISSION  OF  INFORMATION 


443 


tion  of  science  to  the  usual  business  of  life,  while  it  has  multiplied 
the  comforts  of  man  and  perhaps  increased  his  welfare,  has  also 
enormously  augmented  his  killing  powers. 

There  are  still  people  of  intelligence  who  in  practice  think  that 
the  transmission  of  military  thought  is  summed  up  in  the  use  of 
notebook,  the  orderly  and  his  horse.  But  these  are  passing  and 
the  trained  soldier  and  educated  volunteer  understand  the  vital 
importance  of  time  in  military  operations  and  the  need  for  the 
immediate  transmission  of  information.  Hence, the  necessity  for  a 


WHEREAS  HALF  A  CENTURY  AGO  RAPIDITY  OF  TRANSMISSION 

OF    INFORMATION    WAS    MEASURED    BY    THE     SPEED    OF 

COURIERS,  MODERN  ARMIES  EMPLOY  ELECTRICITY  FOR 

DISSEMINATION  OF  MILITARY  INTELLIGENCE, 

.USING   INSTRUMENTS   SIMILAR  TO  THE 

EFFICIENT     LITTLE     BUZZER, 

HERE  ILLUSTRATED 

signal  corps  or  its  equivalent ;  for  without  its  aid  modern  armies 
can  no  more  be  controlled  than  can  great  railway  systems ;  the 
commander  in  the  field  remains  blind  and  deaf  to  the  events  occur- 
ring around  him,  incapable  of  maintaining  touch  with  conditions, 
and  out  of  reach  of  his  superiors  or  those  tinder  his  authority,  upon 
whom  he  depend*  for  the  execution  of  his  plans.  The  brain  lacks 


444  MILITARY  SIGNAL  CORPS  MANUAL 

the  power  to  control  because  the  nerves  are  wanting.  Time  is  the 
main  factor  in  war;  to  arrive  first  with  the  greatest  number  of 
men,  and  with  the  clearest  understanding  of  the  situation,  is  to  suc- 
ceed. The  last,  and  often  the  first,  of  these  conditions  depends  upon 
the  lines  of  information  of  the  army. 

Half  a  century  ago  rapidity  of  transmission  of  information  in 
campaigns  was  in  general  measured  by  the  speed  of  the  couriers; 
distant  movements  were  left  to  take  care  of  themselves  or  neglected, 
since,  if  discovered,  they  could  only  be  reported  after  the  event; 
immediate  operations  were  limited ;  the  chessboard  was  small.  Now 
all  this  is  changed,  and  if  everything  concerned  in  war  and  with  the 
efficiency  of  armies  should  be  of  the  best,  certain  it  is  that  the 
nerves  extending  from  the  controlling  brain  to  the  striking  arm — 
that  is,  the  lines  of  thought  transmission — should  be  the  most  per- 
fect, the  most  rapid,  and  the  most  certain  that  science  can  give. 
Only  the  best  should  find  a  place.  Air  service,  the  radio,  telegraph, 
telephone,  and  visual  signaling  apparatus,  all  must  be  supreme  of 
their  kind  lest  a  club  be  placed  in  the  enemy's  hands,  to  our  own 
destruction. 

If  a  commander's  service  of  information  is  better  than  that  of 
his  adversary  he  posseses  wider  knowledge  and  superior  control ; 
he  selects  with  certainty  his  objective  and  arrives  at  it  first;  he 
perceives  weakness  before  his  own  is  discovered  or  strength  before 
his  weakness  is  known ;  he  anticipates  movements,  alters  disposi- 
tions, executes  plans  unknown  to  his  enemy;  in  short,  the  successful 
soldier  commands  the  situation  by  force  of  superior  knowledge. 
Never  is  it  more  true  than  in  war,  that  knowledge  is  power. 

But  the  kind  of  knowledge  commended  by  the  adage  is  not 
merely  that  acquired  by  stress  of  effort;  it  should  embrace  that 
knowledge  which  comes  from  information  regarding  passing  con- 
ditions, which  alters  with  them  and  changes  from  moment  to  mo- 
ment as  the  shadows  change.  It  is  the  comprehension  upon  which 
successful  action  depends  and  without  which  few  of  the  under- 
takings of  war  can  be  brought  to  a  successful  conclusion.  The  means 
of  securing  this  knowledge  of  events  as  they  occur  and  conditions 
as  they  exist  are  vital  in  warfare.  The  commander  inferior  to  his 
enemy  in  the  character  and  service  of  his  intelligence  communica- 
tion is  like  a  blind  man  fighting  one  who  can  see.  His  information 
service  must  be  of  the  best,  and  also  that  he  must  be  able  to  use 
it  to  the  fullest  extent.  Two  great  means  to  this  end  have  been 
placed  in  the  hands  of  the  modern  general — electricity  and  the  air- 
plane. 


GENERAL  INSTRUCTIONS  FOR  ARMY  SIGNALING 

To  each  signal  station  in  a  military  unit  is  assigned  a  call,  con- 
sisting of  one  or  two  letters,  as  Washington,  "W";  and  each  operator 
01  signalman  also  has  his  personal  signal  of  one  or  two  letters  as 
Jones,  "J."  These  being  once  adopted  they  cannot  be  changed 
without  due  authority. 

To  lessen  the  liability  of  error,  numerals  which  occur  in  the  body 
of  the  message  a  e  spelled  out  in  full. 

In  receiving  a  message  the  man  at  the  telescope  calls  out  each 
letter  as  received,  and  does  not  wait  for  the  completion  of  a  word. 

A  recof1  of  the  'ate,  and  time  of  the  receipt  or  transmission  of 
every  message  mmt  be  kept. 

Duplicate  manuscripts  of  messages  received  at,  or  the  original 
sent  from,  a  station  must  be  carefully  filed. 

In  receiving  messages  nothing  is  taken  for  granted,  and  nothing 
considered  as  seen  until  it  has  been  positively  and  clearly  in  view. 
Signalmen  must  not  anticipate  what  will  follow  from  the  signals 
already  given.  The  communicating  station  must  be  watched  until 
the  last  signals  are  made,  and  the  receiver  must  be  very  certain  that 
the  signals  for  the  end  of  the  message  have  been  given. 

Every  addres  must  contain  at  least  two  words  and  be  sufficient 
to  secure  delivery. 

All  that  the  sender  writes  for  transmission  after  the  word  "To" 
is  counted. 

Whenever  more  than  one  signature  is  attached  to  a  message,  all 
initials  and  names  are  counted  as  part  of  the  message. 

Dictionary  words,  initial  letters,  surnames  of  persons,  names 
of  cities,  towns,  villages,  states  and  territories,  or  names  of  the  Cana- 
dian provinces  are  counted  as  one  word ;  thus :  New  York,  District 
of  Columbia,  East  St.  Louis  should  each  be  counted  as  one  word. 
The  abbreviation  of  the  names  of  cities,  towns,  villages,  states  and 
territories,  and  provinces  are  counted  the  same  as  if  written  in  full. 

Abbreviations  of  weights  and  measures  in  common  use,  figures, 
decimal  points,  powers  of  division,  and  in  ordinal  numbers  the 
affixes  l-st".  "d",  "nd",  "rd",  and  "th"  will  each  be  counted  as  one 
word.  Letters  and  groups  of  letters,  when  such  groups  do  not  form 

445 


446  MILITARY  SIGNAL  CORPS  MANUAL 

dictionary  words  and  are  not  combinations  of  dictionary  words,  are 
counted  at  the  rate  of  five  letters  or  fraction  of  five  letters  to  a 
word.  When  such  groups  are  made  up  of  combinations  of  dictionary 
words,  each  dictionary  word  so  used  is  counted. 

The  following  are  exceptions  to  the  preceding  paragraph,  and  are 
counted  as  shown :  A.M.,  1  word ;  P.M.,  1  word ;  O.K.,  1  word ;  Per 
cent,  1  word. 

ORDER  OF  TRANSMISSION  OF  SEALED  MESSAGES 

The  sending  operator  enters  the  time,  when  the  message  is  handed 
him  for  transmission  in  the  left  hand  corner  at  the  bottom  blank 
opposite  the  word  "Received."  He  then  enters  in  the  proper  places, 
at  the  head  of  the  blank,  the  number  of  the  message,  the  call  letter 
of  the  transmitting  station,  the  operator's  personal  signal,  the  check 
(the  number  of  words  or  groups  of  ciphers  contained  in  the  message, 
counting  address  and  signature),  and  after  "R"  or  "OK"  has  been 
received  he  enters  the  time  the  message  is  sent  and  the  call  letter 
of  the  receiving  station,  with  the  personal  signal  of  the  receiving 
operator. 

In  transmitting  a  message  the  operator  sends  (1)  the  number 
of  the  message  and  call  letter  of  his  station ;  (2)  his  personal  signal ; 
(3)  the  check;  (4)  "fm,"  followed  by  the  name  of  the  sending 
detachment;  (5)  "at,"  followed  by  the  location  of  the  sending 
detachment  and  date;  (6)  "ho",  followed  by  the  hour  (a.m.  or  p.m.) 
message  was  written;  (7)  "to"  followed  by  the  address  in  full;  (8) 
Period  (.  .  -  -  .  .)  ;  (9)  body  or  text  of  the  message;  (10)  "sig," 
followed  by  the  signature  of  the  message. 

The  following  message  is  an  example : 

First  Army  Corps,  San  Antonio,  Tex. 
10  a.m.,  June  31,  1916. 
General  Blanke, 

El  Paso,  Tex. 

The  Deming  force  will  return  at  once  to  Ysleta  and  protect  the 
bridge.  I  will  cover  Laredo. 

A.  B.  Usher,  Major  General. 

This  would  be  sent : 

No.  1  K  Jo  ck  26  OFM  fm  1st  Army  Corps  at  San  Antonio  Tex  6 
ho  10  am  to  General  Blanke  El  Paso  Tex  .  .  -  -  .  .  (period)  The 
Deming  force  will  return  at  once  to  Ysleta  and  protect  the  bridge  I 
will  cover  Laredo  sig  A  B  Usher  Major  General 

Note — Above  example  illustrates  the  method  of  transmitting  mes- 
sages over  fielJ  lines  by  operators  using  the  American  Morse  Code. 

Where  the  International  Morse  Code  is  used  as  means  of  trans- 
mission, the  double  dash  (-  .  .  .  -)  is  inserted  in  the  place  of  "to," 
''period,"  and  "sig." 


THE   AMERICAN    MORSE  CODE 

The  American  Morse  code  is  used  officially  by  the  Army  only  for 

electrical  signaling  on  telegraph  lines,  on  short  cables,  and  field  lines. 
It  is  written  as  follows: 

Alphabet. 

A    .—  N    — . 

B    -...  O    .    . 

C    ..    .  P    

D    -..  Q    .._. 

E    .  R    .    .. 

F    .-.  S    ... 

G .  T    - 

H    ....  U    ..- 

I    ..  V    ...— 

J    -.-.  W    . 

K    -.—  X    .  — .. 

L  Y    ..    .. 

M  Z    ...    . 

&    .    ... 
Numerals. 

1  . .  6    

2  ..  — ..  7 .. 

3  ...-.  8    -.... 

4  ....—  9    — ..— 

5  -  0 

Punctuation. 

Period     .. 

Comma —  •  — 

Interrogation     — ..  — . 

Hyphen     (HX)  — .. 

Dash    (DX)  —        .  — .. 

Parenthesis    (begin)     (PN)  — . 

Parenthesis    (end)     (PY)  

Quotation    marks     (begin) (QN)  ..  — .    — . 

Quotation  marks  (end) (QJ)  ••  —  •    — •  —  • 

447 


448  MILITARY  SIGNAL  CORPS  MANUAL 

Punctuation —  ( Continued  ) 

Dollar  mark (SX)      ...    .  — .. 

Decimal    point Spell  "dot." 

Capitalized  letter (CX)     ..    .    .  — .. 

Semicolon    (SI)       

Underline   (begin)    (UX)     ..—    .  — .. 

Underline  (end)   (UJ)      ..—    — .  — . 

Colon  dash (KX)     -.-     .  — .. 

Colon  followed  by  quotation.  (KQ)     — . —    ..  — . 

Exclamation    point (  !) . 

Fraction  bar (/)     . 

Paragraph  mark   (  <j ) 

Pounds,   sterling (£)      (PX) — . . 

Shilling  mark  (UT)  . .  —    '• 

Abbreviations. 

af after  nite night 

ahr another  nl night    letter 

b be  npr night  press  rate 

bf before  ob official   business 

bn been  pd paid 

ck check  r are 

en can  t the 

da day  u you 

dl day   letter  ur your 

dpr day  press  rate  w with 

fm from  wrd word 

gn. good-night  x  (in  check) get    a    reply    to 

govt government  this  message 

hr hear  or  here  5 Have    you    any- 

hv have  thing  for  me  ? 

msg message  13 understand 

Conventional  Signals  for  Use  With  the  American  Morse  Code. 

The   following   conventional    signals    will   be   used    on    military 
telegraph  lines,  short  cables,  and  field  lines: 

Attention,   all   operators (9)  —  .  .  — 

Please  start  me  (or)  where  shall  I  start. .  (4)   ....  — 

Wait  a  moment (MIN) .  .    — . 

Official  message    (OFM)  .    .    .  —  . 

I   understand (OK)  .    . 

Busy  on  other  wires (25)  .  .  —  .  . 

No  more   (NM)  —  . 

Test,    give   away (WIRE)  . 

Break    (BK)  —  ...    —  .  — 

Go  ahead   (GA)  —  —  .    .  — 

Error    (DN)  —  .  .    — . 

Signature    follows    (sic) . 


THE    INTERNATIONAL  MORSE   OR   GENERAL   SERVICE 

CODE 

The  international  Morse  Code  is  the  General  Service  Code  for 
use  by  the  Arrn>  of  the  United  States  and  between  the  Army  and 
X'avy  of  the  United  States.  It  is  employed  in  all  visual  signaling 
apparatus  using  the  wig-wag,  radio  telegraphy,  and  on  cables  using 
siphon  recorders.  There  is  but  one  modification  in  its  use,  that  is, 
when  the  Ardois  night  system  is  used  numerals  shall  be  spelled 
out  and  punctuation  marks  shall  be  eliminated.  The  use  of  the 
international  Morse  code,  however,  does  not  prohibit  the  employ- 
ment between  the  Army  and  Navy  of  such  other  systems  of  sig- 
naling as  may  be  useful  under  special  conditions,  such  as  the  In- 
ternational Code,  the  two-arm  semaphore  system,  pyrotechnics  of 
any  description,  including  rockets,  the  Very  pistol,  or  any  other 
method  of  communication  not  adapted  to  the  dot-and-dash  code, 
but  which  at  times  may  become  serviceable  and  which  may  be 
temporarily  agreed  to  by  the  senior  officer  of  the  two  services. 
The  international  Morse,  or  General  Service  Code,  is  written  as 
follows : 

Alphabet. 
A  .  -  N  -  . 

B  -.  .  .  O 

C-  .  -  .  P  . . 

D-  .   .  Q_     _._ 

E  .  R  .  -  . 

F..-.  S... 

G-     -.  T- 

H U  .  .- 

I    .  •                                                                 V  .  .  .  _ 
J.  •  -  W  . 

k"    _  Y 

"^  •  A.    .    .    

L  .  —  .  .  Y  — 

M Z 

Numerals. 
1  . 6'  — „.; 

3  !  '.  . S —  [ 

4  .  .  .  .  _  9 

5  .  0  - 


449 


450  MILITARY  SIGNAL  CORPS  MANUAL 

Punctuation. 

Period    

Comma    - •  —  •  —  •  — 

Interrogation     • •    • 

Hyphen  or  dash —  •    •    •    •  — 

Parenthesis  (before  and  after  the  words).. —  • •  — 

Quotation  mark  (beginning  and  ending)   .  —  •    •  —  • 

Exclamation    •    • 

Apostrophe     • 

Semicolon •• —  •  —  •  —  • 

Colon  .    •   • 

Bar   indicating    fraction —  .    .  —  . 

Underline  (before  and  after  the  word  or  words  it 

is  wished  to  underline) .  — 

Double  dash  (between  preamble  and  address,  be- 
tween address  and  body  of  message,  between  body 
and  signature,  and  immediately  before  a 

fraction)    —  .    .   .  — 

Cross    .  —  .  —  . 

CONVENTIONAL   SIGNALS   FOR   USE  BY   RADIO    STATIONS   WITH   THE 
INTERNATIONAL   MORSE   CODE 

The  following  conventional  signals  will  be  used  by  radio  sta- 
tions of  the  United  States  Army  with  the  International  Morse 
Code  : 

Distress  signal  (ship  stations  only)  —  SOS   (-•• ---) 

Attention  (or  call)   The  call   is  composed  of  the  attention 

signal  KA  ( — )  followed  by  the 

call   letters  of  the   station   called,   re- 
peated three   times   [if  unknown   use 

CQ    ( — —    — )   in    place   of    call 

letters    of    station    called],     followed 

by    DE    ( -)    and    then    the    call 

letters     of    the     calling     station,     re- 
peated three  times. 

Have  you  anything  for  me QRU  ( ) 

How  many  words  have  you  to  send....QRJ    ( ) 

Invitation   to  transmit   (go  ahead) K  ( ) 

Signal    separating    preamble    from    ad- 
dress,   address    from    text,    and    text 

from   signature   BT  ( — •••    — ) 

End  of  message   RN  ( — ) 

End  of  work SK  (--• ),  followed  by  the  call  let- 
ter of  sending  station  and  K   ( ) 

Received    (acknowledgment    of    receipt 

of  message)  R  ( ),  followed  by  the  call  letter  of 

the    receiving    station    and    personal 
signal  of  the  receiving  operator. 

Here   is   another   message KA  ( — )  attention  call. 

Understood  (or  I  understand) SN   (---  — ),   followed   by   the  call   let- 
ter of   station. 

Not  understood  (or  repeat)   Signal    interrogation    ?    ( — -)    and 

the  last  word  received. 

Error    (or    mistake) Signal   eight   dots    ( ) 

Wait    —  --- 

Official  message   OFM   ( — — ) 


INTERNATIONAL  MORSE  OR  GENERAL  451 

SERVICE  CODE 

(First  word  of  preamble  on  all   radio- 
grams)     RADIO    ( ) 

Faster QRQ   ( ) 

Slower    QRS  ( "*) 

Stop  sending  QRT  ( — ) 

Interference  XX   ( ) 

Use  International  Code  of  Signals PRB  ( ) 

General  inquiry  call  (when  call  of  sta- 
tion is  not  known) CQ  ( )  (see  attention  call) 

How  do  you  receive  me QRK  ( ) 

TRANSMISSION  OF  MESSAGES  BY  INTERNATIONAL  MORSE 


EXAMPLE 

WVB  sending  to  WVA  a  plain  commercial  message  filed  at 
4  p.  m.,  of  the  12th,  after  receiving 

RADIO 

Circle  City Office  of  destination. 

De. 

Fairbanks   Office  of  origin. 

2    Number  of  message. 

L  Operator's  sign. 

8  Check. 

Twelfth  4  p.  m Date  and  hour  of  filing 

Break   or   double   dash. 

Brown,  175  King  Street. 

Circle  City   Address. 

Break. 

Arrive   tomorrow Text. 

Break. 

Jones   Signature. 

KMO 


INSTRUCTION  IN  GARRISON 

VISUAL  STATIONS 

The  alphabet  and  conventional  signals  with  the  flag  should 
be  thoroughly  mastered  by  means  of  wand  drill,  instruction  in  which 
is  to  be  given  regularly  at  such  time  as  prescribed  by  the  company 
commander. 

Signal  parties  should  consist  of  four  men,  equipped  with  the 
necessary  visual  signal  equipment  for  the  operation  of  one  sta- 
tion. The  instructor  selects  the  point  where  the  station  is  to  be 
established  and  gives  the  location  of  the  station  or  stations  with 
which  communication  is  to  be  conducted. 

At  the  command  open  station,  the  signal  equipment  is  made 
ready  for  use. 

One  man  is  designated  to  record  incoming  messages  and  to  call 
x>ff  the  words  of  the  message  being  sent. 

A  second  man  manipulates  the  sending  equipment  and  reads 
and  calls  off  incoming  messages  for  the  recorder. 

A  third  man  watches  the  distant  station  for  breaks. 

A  fourth  man  is  messenger. 

The  signal  party  is  made  familiar  with  the  various  duties  by 
frequently  changing  about  the  four  men  to  execute  each  other's 
tasks. 

Outside  or  field  work  is  conducted  by  sections,  which  may 
be  divided  into  convenient  squads  of  four,  chiefs  of  sections  and 
their  assistants  being  the  instructors.  These  units  lend  themselves 
readily  to  the  use  of  the  flag,  heliograph,  and  lantern,  as  well  as 
for  convenience  in  camping. 

TELEGRAPHY 

Ability  to  telegraph  by  means  of  the  American  Morse  code  is 
a  most  important  qualification  for  members  of  the  Signal  Corps. 
Only  those  who  have  adaptability  for  operating  and  are  sufficiently 
educated  should  be  given  this  instruction. 

The  instruction  should  be  conducted  in  classes,  under  the 
direction  of  the  company  commander,  by  competent  noncommis- 
sioned officers,  and,  when  practicable  under  the  personal  super- 

452 


INSTRUCTION  IN   TELEGRAPHY  453 

vision  of  a  commissioned  officer.  The  buzzer  is  used  for  this  in- 
struction and  the  men  classified  according  to  ability  and  progress. 
Instruction  indoors  is  to  be  continued  until  the  operator  is  suffi- 
ciently advanced  to  work  to  advantage  on  field  lines,  that  is,  when 
he  has  acquired  ability  to  send  and  receive  about  15  words  per 
minute  under  service  conditions. 

Instruments  should  be  provided  in  company  headquarters  so 
that  they  are  accessible  to  the  members  at  all  times,  encouraging 
the  ambitious  to  rapid  progress.  Opportunity  should  also  be  given 
to  use  typewriters  when  members  have  progressed  sufficiently. 

The  standard  instruction  of  the  United  States  Army  for  teleg- 
raphy serves  as  an  excellent  guide  and  is  given  here  for  the  in- 
formation of  all  instructors. 

The  Morse  code  as  used  in  the  Signal  Corps  consists  of  seven 
elements:  (1)  the  dot;  (2)  the  dash;  (3)  the  long  dash;  (4)  the 
ordinary  space;  (5)  the  letter  space;  (6)  the  word  space;  and 
(7)  the  sentence  space.  It  is  important  to  remember  that  the 
value  of  the  spaces  in  the  code  is  as  great  as  that  of  the  dots 
and  dashes.  The  complete  code  is  shown  in  the  accompanying 
plates. 

The  arbitrary  unit  of  time  in  this  code,  which,  when  writtea 
down  becomes  a  unit  of  length,  is  technically  termed  the  dot.  An 
appreciable  time  is  required  for  the  production  of  signals  by  elec- 
tricity, in  the  magnetization  of  the  electromagnet,  and  in  the 
movement  of  clockwork.  The  formation  of  a  dot,  therefore, 
necessarily  involves  time.  Assuming,  therefore,  that — 

(1)  the  dot  is  the  unit  of  time. 

(2)  The  dash  is  equal  to  two  dots. 

(3)  The  long  dash  is  equal  to  four  dots. 

(4)  The  ordinary  space  ncvween  the  elements  of  a  letter  is 

equal  to  one  dot. 

(5)  The  letter  space  is  equal  to  two  dots; 

(6)  The  word  space  is  equal  to  three  dots. 

(7)  The  sentence  space  is  equal  to  six  dots. 

The  recruit  will  first  thoroughly  commit  to  memory  the  groups 
of  signs  representing  the  letters  of  the  alphabet,  the  numerals, 
and  the  principal  punctuation  points,  viz.,  the  period,  the  comma, 
and  the  point  of  interrogation.  The  remaining  characters  can  be 
learned  afterwards,  as  they  will  be  little  needed  by  the  beginner. 

The  most  approved  manner  of  grasping  the  key,  and  one 
which  has  been  employed  by  some  of  the  most  successful,  ex- 
perienced, and  rapid  operators,  is  shown  in  the  illustration.  Curve 
the  forefinger,  but  do  not  hold  it  rigid.  Let  the  thumb  press 
slightly  in  an  upward  direction  against  the  knob.  Keep  the  wrist 
well  above  the  table.  Xo  better  general  direction  can  be  given 
than  that  the  key  will  be  grasped,  held,  and  controlled  with  the 


454  MILITARY  SIGNAL  CORPS  MANUAL 

same  flexible  but  perfectly  controlled  muscular  action  of  the 
fingers,  wrist,  and  forearm  with  which  the  skilled  penman  holds 
his  pen.  Carefully  avoid  tapping  upon  the  knob  of  the  key;  the 
raising  spring  should  assist  the  upward  motion  of  the  key,  but 
should  never  be  permitted  to  control  it. 


CORRECT  MANNER  OF  GRASPING   KEY   IN  TELEGRAPHING 

By  constant  drill,  as  hereinafter  directed,  the  habit  of  making 
dots  with  regularity,  uniformity  and  precision  must  first  be  ac- 
quired; then  dashes,  and  lastly,  in  order,  group  of  dots  and 
dashes,  letters  and  words.  In  commencing,  the  habit  should  at 
once  be  acquired  of  making  the  dots  like  short,  firm  dashes. 
The  recruit  should  learn  to  form  the  conventional  characters 
accurately  and  perfectly;  speed  will  come  in  good  time,  but  only 
as  a  result  of  constant  and  persistent  drill. 

ELEMENTARY   PRINCIPLES 

As  a  basis  for  practice,  the  code  may  be  regarded  as  comprisir- 
six  elementary  principles,  viz. : 

First  principle — Associated   dots. 
i  s  H  p  6 

Second  principle — Associated  dashes. 
M  5  fl 

Third  principle — Isolated  dots. 
E 

Fourth  principle — Isolated   dashes. 
L  or  cipher  T 

Fifth  principle — Dot  followed  by  dash. 


Sixth  principle — Dash  followed  by  dot, 
N 

The  learner's  first  practice  is  upon  these  elementary  princi- 
ples. 


INSTRUCTION  IN   TELEGRAPHY  455 

PUNCTUATION    AND    .MISCELLANY 


Comma,  » 

Semicolon,  ; 

Colon,  : 

Colon  Dub,  :— 

Period,  . 

Interrogation,  ? 

Exclamation,  ! 

Dash,  — 
Hyphen, 

Pounds,*  & 

Shillings,1  / 

Dollars,1  $ 
Capitalized  Letter,1 

Colon-Quotation,  ;  < 

Decimal  Point,  • 

Paragraph,  H 

Parenthesis,*  (  ] 
Underline,1 
Quotation,* 
Quotation  within  Quotation,1  "  * 


(3)  The  long  Jath  is  equal  to  4  dots  ;. 

(4)  The  ordinary  space  between  the  elements  of  a  letter  is  equal  to  1  dot ; 

(5)  The  Ulttr-tpacc  is  equal  to  2  dots  ; 

(6)  The  -werj.ifacf  is  equal  to  3  dots ; 

(7)  The  unUmtt-tfate  is  equal  to  6  dots. 

1  To  be  uteri  before  the  tharactert  to  which  it  refers. 

»  To  be  BMd  before  and  »fur  the  werdi  to  which  it  retro., 


456 


MILITARY  SIGNAL  CORPS  MANUAL 


Make  dots  with  the  key  at  uniform  and 
they  can  be  produced  with  the  precision 
definite  and  uniform  dimensions. 

Next  make  dashes,  first  at  the  rate  of 
which  speed  may  be  increased  by  degrees, 
practice,  to  three  per  second.  Make  the 
successive  dashes  as  short  as  possible.  If 
which  forms  the  space  be  made  full,  it 
quickly. 

The    third    principle    occurs    but    once, 
directions. 


regular  intervals,  until 
of  a  machine  and  of 

about  one  per  second, 
as  skill  is  acquired  by 
space  interval  between 
the  upward  movement 
can  not  be  made  too 

and    needs    no    specific 


ALPHABET    AND    NUMERALS 


A      •     •• 

N 

.. 

• 

I      !      •! 

•  II 

fi      i  i     • 

C.     . 

•     •           O 

•                              p 

• 

• 

9111 

1      1      1 

•     • 
D     ii     • 

i 

•             Q 

, 

i   • 

i   • 

3III 

4     i     i     • 

I      II 

E     • 

R 

• 

• 

i 

S    ii    •• 

1  1 

F     ill 

•                 S 

• 

i   • 

GUI 

i     i              T 

7     ii     •• 

I      1 

H     i     i 

•         u 

•   i 

i   • 

i 

8     ii     i 

1      1      1 

I       i     i 

V 

• 

i   • 

i- 

9     ii     • 

1      II 

J      ••     i 

•  ii        W 

• 

i  • 

1  1 

0      |  B  i  i  H 

K     !•• 

•  i              X 

i 

i  H 

t      m 

L    •••• 

y 

• 

i 

1       • 

M     ••     • 

z 

•   i 

i   • 

• 

& 

• 

I       • 

The  fourth  principle  will  be  found  somewhat  more  difficult 
to  execute.  The  usual  tendency  is  to  make  T  too  long  and  L  too 
short.  Theoretically,  the  cipher  is  one-half  longer  than  L,  but  in 
fact  it  is  always  made  the  same,  as  the  practice  has  been  found 
to  occasion  no  inconvenience.  Occurring  alone  or  among  other 
letters,  it  is  translated  as  L,  but  when  found  among  figures  it  is 
read  as  0. 

The  fifth  principle  forms  the  letter  A.  The  usual  tendency  is 
to  separate  the  two  elements  too  much. 

The  dash  followed  by  a  dot  (N)  is  usually  found  to  be  some- 
what difficult.  Time  the  movement  by  pronouncing  the  word 


INSTRUCTION  IN   TELEGRAPHY  457 

ninety,   sounding  the  first  syllable   fully.     Guard   especially  against 
the  usual  tendency  to  separate  the  elements  by  too  great  a  space. 

Having    become,    thoroughly    familiar    with    the    principles,    the 
following  exercises  may  with  advantage  1     taken  up  in  order : 

E      i        s          H  P  6 


These  should  be  practiced  repeatedly  until  the  correct  number 
of  dots  in  each  character  can  be  certainly  made  at  every  trial.  A 
habit  once  formed  of  making  the  wrong  number,  usually  one  or 
two  too  many  in  the  case  of  H,  P,  and  6,  is  almost  impossible 
to  eradicate.  Guard  especially  against  the  objectionable  habit 
of  shortening  or  clipping  the  final  dot,  a  vice  which  leads  to 
innumerable  and  vexatious  errors  and  misreading  of  signals. 

T  M  5  fl 

The  faults  to  guard  against  particularly  in  this  exercise  are 
shortening  or  elongating  the  terminal  dash,  and  separating  the 
successive  dashes  by  too  great  a  space  interval. 

A        U  V  4 

The  usual  tendency  to  allow  too  much  space  between  the  dot 
and  dash  in  the  above  letters  may  be  overcome  by  forming 
them  as  by  an  elongation  of  the  final  dot  in  I,  S,  H,  and  P. 

I       A        S         U          H  V 


Practice  these  characters  in  pairs,  that  the  distinction  be- 
tween them  may  be  more  firmly  impressed  upon  the  mind. 

N         D  B  8 

The  student  who  has  mastered  the  sixth  principle  will  find 
no  difficulty  with  the  above  characters. 
AFX 


W  1 

U  Q  2  Period 


These  are  simitar  to  preceding  exercises,  and  present  no  new 
difficulties. 


458  MILITARY  SIGNAL  CORPS  MANUAL 

K  J  9  7 

J  and  K  are  usually  considered  the  most  difficult  letters  in 
the  code.  Avoid  the  tendency  to  separate  J  by  a  space  into 
double  N,  and  be  careful  that  the  dashes  are  of  equal  length. 
The  numerals  7  and  9  require  some  care  to  insure  correct 
spacing. 

O       R          &          C 


These  are  termed  the  space  letters,  and  the  utmost  care  and 
diligent  practice  are  necessary  in  order  to  form  them  accurate- 
ly. The  ability  to  transmit  the  spaced  letters  with  absolute 
correctness  is  the  test  of  a  strictly  first-class  sender.  The 
space  should  be  just  enough  in  excess  of  that  ordinarily  used 
between  the  elements  of  a  letter  to  enable  the  letters  intended 
to  be  made  to  be  distinguished  with  certainty  from  I,  S,  and  H. 
The  most  usual  tendency  is  to  make  the  space  too  great,  even 
in  some  cases  as  great  as  the  space  between  letters.  This  is  a 
most  fruitful  source  of  misapprehension  and  error,  and  too 
much  pains  can  not  be  taken  to  acquire  and  maintain  correct 
habits  in  this  particular. 

METHODS  OF  PRACTICE 

In  transmitting  words  containing  groups  of  two  or  more 
spaced  letters,  careful  operators  are  accustomed  to  slightly 
increase  the  spacing  between  successive  letters  of  the  group. 

Practice  in  transmission  from  miscellaneous  manuscript  is 
strongly  recommended.  The  ability  to  read  all  kinds  of  copy — 
good,  bad,  and  indifferent — correctly  at  sight  is  a  most  valuable 
one,  and  it  is  not  difficult  to  acquire  by  attention  and  ex- 
perience. 

If  the  principles  here  laid  down  be  firmly  adhered  to,  the 
learner  will  find  much  reason  for  encouragement  not  only  at 
the  rapidity  with  which  he  will  master  what  at  first  sight  ap- 
pears to  be  a  very  difficult  undertaking,  but  the  extreme  accu- 
racy with  which  he  will  be  able  to  manipulate  his  instrument 
after  a  fair  amount  of  practice. 

This  art  can  only  be  acquired  by  constant  and  persevering 
practice,  keeping  in  mind  the  principles  above  given. 

In  learning  to  read  by  sound,  it  is  advisable  for  two  per- 
sons to  practice  together,  taking  turns  at  reading  and  writ- 
ing, and  each  correcting  the  faults  of  the  other.  The  sounds 
of  the  code  characters  must  first  be  learned  separately  and  then 
short  words  chosen,  which  must  be  written  very  slowly  and 
distinctly  and  well  spaced,  the  speed  of  manipulation  being 


IXSTRUCTION  IN  TELEGRAPHY  459 

gradually  increased  as  the  student  becomes  more  proficient  in 
reading. 

When  the  operator  has  made  sufficient  progress,  he  will  be  given 
instruction  in  checking  messages,  the  conduct  of  offices,  the  care, 
adjustment,  and  repair  of  instruments. 

CHECKING  THE  MESSAGE 

In  preparing  the  "check"  of  the  message,  all  words  and 
figures  written  in  the  address,  body  of  the  message,  and  the  signa- 
ture will  be  counted.  That  is,  count  all  words  after  to  to  the 
end  of  the  signature.  The  word  "sig."  is  sent  merely  to  indi- 
cate that  the  signature  follows,  and  is  not  counted  in  the  check. 

In  counting  the  check  of  a  message,  all  words,  whether  in 
plain  English,  code,  or  cipher,  pronounceable  or  unpronounce- 
able, or  initial  letters,  will  be  counted  each  as  one  word.  The 
abbreviations  for  the  names  of  places,  cities,  towns,  villages, 
States,  Territories,  and  Provinces  will  be  counted  as  if  written 
in  full.  In  the  names  of  towns,  counties,  countries,  or  States 
all  of  the  words  will  be  counted. 

Abbreviations  of  weights  and  measures  in  common  use  and 
cardinal  points  of  the  compass  will  be  counted  each  as  one 
word. 

Figures,  decimal  points,  and  bars  of  division,  and  letters  will 
be  counted  each  separately  as  one  word. 

In  ordinal  numbers,  the  affixes  st,  d,  nd,  rd,  and  th  will  each 
be  counted  as  one  word. 

PRACTICE  IN  RECEIVING 

Ability  to  read  messages,  land  telegraph  or  wireless,  is  prob- 
ably best  acquired  by  group  study,  a  proficient  operator  sending 
to  a  class  by  means  of  individual  instruments  connected  to 
the  instructor's  transmitter.  Receiving  is  much  more  difficult 
than  sending  and  acquiring  proficiency  is  a  long  and  laborious 
process,  in  comparison  with  the  comparatively  simple  mastery 
of  sending.  The  Government  in  many  of  its  examinations  for 
operators  uses  a  small  machine  known  as  the  Omnigraph,  a 
clock-work  mechanism  which  sends  messages  by  rotating  alu- 
minum disks  with  cut  edges  which  break  the  circuit  into  dots 
and  dashes. 

This  device  has  many  advantages  for  instructing  signalmen, 
notably  that  perfect  sending  is  assured  and  elasticity  of  sub- 
ject matter  extended  by  the  slide  changers  to  innumerable 
combinations.  Morse  and  International  may  be  sent  at  speeds 
from  5  to  100  words  a  minute.  Recruit  instruction  should  be 
arranged  so  that  the  signalmen  can  use  all  odd  hours  for 
practice,  and  every  encouragement  should  be  given  to  men 
showing  aptitude  and  ambition. 


460  MILITARY  SIGNAL  CORPS  MANUAL^ 

The  receiving  operator  adds  to  the  message  after  it  is  received  the 
month  and  year  and,  after  satisfying  himself  that  the  checked 
number  of  words  corresponds,  gives  "R"  followed  by  the  call  letter 
of  his  station  and  his  own  personal  signal.*  The  operator  then  enters 
in  the  proper  places  at  the  head  of  the  blank  call  letter  of  his  own 
station,  with  his  personal  signal  and  the  time  the  message  was  re- 
ceived. 

Communications  transmitted  by  telegraph  or  signals  are  always 
confidential  and  are  revealed  only  to  those  officially  entitled  to 
receive  them. 

When  everal  messages  are  to  be  sent  in  succession  "end  of  mes- 
sage" signal  is  made  after  the  signature  of  each,  to  be  followed  by 
the  abbreviation  "ahr,"  meaning  "another,"  after  which  the  sending 
of  the  next  me  sage  is  begun. 

No  message  is  considered  sent  until  its  receipt  has  been  acknowl- 
edged by  the  receiving  station. 

•On  military  telegraph  lines,  short  cables,  and  field  lines  the  receipt  of  a 
message  is  acknowledged  by  the  signal  "  OK." 


VISUAL  SIGNALING  IN  GENERAL 

Methods  of  visual  signaling  are  divided  as  follows: 

(a)  By    flag,    torch,   hand    lantern,   or   beam   of    searchlight 
(without  shutter).     (General  Service  Code.) 

(b)  By  heliograph,  flash  lantern,  or  searchlight   (with  shut- 
ter).    (General  Service  Code.) 

(c)  By  Ardois.     (General  Service  Code.) 

(d)  By  hand  flags  or  by  stationary  semaphore.     (Two-arm 
semaphore  Code.) 

(e)  By    preconcerted    signals    with    Coston    lights,    rockets, 
bombs,  Very  pistols,  small  arms,  guns,  etc. 

(/)  By  flag  signals  by  permanent  hoists.  (International 
Code.) 

The  following  conventional  signals,  with  exceptions  noted, 
will  be  used  in  the  first  four  classes. 

Exceptions 

Ardois  and  semaphore. 

End  of  word.  Interval. 

End  of  sentence.  Double  interval. 

End  of  message.  Triple  interval. 

Signal  separating  pream- 
ble   from    address;    ad- 

dress   from    text;    text  Double    interval,    signa- 

from  signature.  ture   preceded   also   by 

Interval. 


Acknowledgment. 

R. 

Error. 

A 

Negative. 

K. 

A. 

Preparatory. 

L. 

Annulling. 

N. 

Affirmative. 

P. 

Interrogatory. 

—  .. 

0. 

Repeat  after  word. 

Interrogatory,  A  (word). 

Repeat  last  message. 

Interrogatory   three  times. 

Send  faster. 

QRQ 

Send  slower. 

ORS 

Cease  sending. 

QRT 

Wait  a  moment. 



No 

Execute. 

IX,  IX 

Move  to  your  right. 

MR 

Move  to  your  left. 

ML 

Move  up. 

MU 

Move  down. 

MD 

Finished   (end   of  work) 



No 

461 


462  MILITARY  SIGNAL  CORPS  MANUAL 

Note. — In  order  to  differentiate  these  signals  from  important 
battle  signals,  the  Navy  uses  certain  distinguishing  variations 
which  are  not  necessary  in  signaling  in  the  Army.  In  making 
the  conventional  signal  for  "A,"  Error,  and  "O,"  Interrogatory, 
in  Ardois,  the  Navy  indicates  them  by  pulsating  the  upper  light, 
in  making  them  in  semaphore,  by  agitating  the  arms  or  flags. 
"K,"  Negative;  "L,"  Preparatory;  "N,"  Annulling;  "O,"  Inter- 
rogatory; and  "P,"  Affirmative,  in  the  Navy  are  secondary 
meanings,  and  are  used  only  in  connection  with  Navy  Code 
Books.  They  should  not  be  used  in  communication  between 
the  Army  and  the  Navy. 

In  communicating  with  the  Navy,  by  all  methods,  numerals 
are  spelled  out. 

"Intervals"  are  expressed  as  follows  in  the  various  systems : 

Interval  Double  Interval      Triple   Interval 

Radio 
Flashing 

Occulting  light    f  —  space 
Sound 

Wigwag  Front  (Twice)  (3  times) 

Semaphore  Flags    crossed    or  2  chops  3      chops,      withdraw 

machine  close J  flags     or     close  _  ma- 

chine    and    indicator 
arm. 
Ardois  — —  (Twice)  (3  times) 


SIGNALING  BY  FLAG,  TORCH,  AND  LANTERN,  OR  BEAM 
OF  SEARCHLIGHT  (WITHOUT  SHUTTER) 

GENERAL   SERVICE   CODE 

For  the  flag  used  in  the  General  Service  Code  there  is  one 
position  and  there  are  three  motions.  The  position  is  with 
the  flag  held  vertically,  the  signalman  facing  directly  toward 
the  station  with  which  it  is  desired  to  communicate.  The  first 
motion  (a  dot)  is  to  the  right  of  the  sender,  and  embraces  an 


SOLDIERS  OF   THE   FORT  WOOD   SIGNAL 

CORPS    SCHOOL    WIG- WAGGING 

MESSAGES  IN  THE   FIELD 

arc  of  90  deg.  starting  with  the  vertical  and  returning  to  it;  it  is 
made  in  a  point  at  right  angles  to  the  line  connecting  the  two 
stations. 

The  second  motion  (the  dash)  is  a  similar  motion  to  the  left 
of  the  sender. 

463 


464  MILITARY  SIGNAL  CORPS  MANUAL 

The  third  motion  (front)  is  downward  directly  in  front  of 
the  sender  and  instantly  returned  upwards  to  the  first  position. 
Front  is  used  to  indicate  an  interval. 

The  beam  of  th«"  searchlight,  though  ordinarily  used  with 
shutter  like  the  heliograph,  may  be  used  for  long-distance 
signaling,  when  no  shutter  is  suitable  or  available,  in  a  similar 
manner  to  the  flag  or  torch,  the  first  position  being  a  vertical 
one.  A  movement  of  the  beam  90  deg.  to  the  right  of  the  sender 
indicates  a  dot,  a  similar  movement  to  the  left  indicates  a  dash  ; 
a  beam  is  lowered  vertically  for  front. 

In  the  use  of  torch  or  hand  lantern,  a  footlight  must  be 
employed  as  the  point  of  reference  to  the  motion.  A  lantern 
is  most  conveniently  swung  out  upward  to  the  right  of  the 
footlight  for  a  dot,  to  the  left  for  a  dash,  and  raised  vertically 
for  front. 


The  first  position  is  to  turn  a  steady  flash  on  the  receiving  station. 
The  signals  are  made  by  short  and  long  flashes.  Use  a  short  flash 
for  dot  and  a  long  steady  flash  for  dash.  The  elements  of  a  letter 
should  be  slightly  longer  than  in  sound  signals. 

To  call  a  station  make  its  call  letter  until  acknowledged. 


If  the  call  letter  of  a  station  be  unknown,  signal  A  until  acknowl- 
edged. Each  station  will  then  turn  on  a  steady  flash  and  adjust. 
When  the  adjustment  is  satisfactory  to  the  called  station,  it  will  cut 
off  its  flash,  and  the  calling  station  will  proceed  with  its  message. 

If  the  receiver  sees  that  the  sender's  mirror  or  light  needs  adjust- 
ment, he  will  turn  on  a  steady  flash  until  answered  by  a  steady 
flash.  When  the  adjustment  is  satisfactory  the  receiver  will  cut 
off  his  flash  and  the  sender  will  resume  his  message. 

To  break  the  sending  station  for  other  purposes,  turn  on  a  steady 
flash. 

It  may  be  noted  that  in  the  daytime  and  in  ordinary  weather  the 
searchlight  with  shutter  can  be  readily  used  for  distances  up  to  10 
miles  at  sea. 

465 


THE  ARDOIS  SYSTEM 

GENERAL  SERVICE  CODE 

The  Ardois  system,  used  in  both  Army  and  Navy,  is  a  display 
of  four  lights,  each  of  which  may  be  made  either  red  or  white. 
These  lights  are  incandescent  lamps,  operated  by  a  keyboard  and 
marked  with  the  appropriate  signal  letters  or  signs. 

The  red  lamp  indicates  a  dot  and  the  white  lamp  a  dash. 

If  the  lights  are  placed  vertically  they  are  read  from  the  top 
downward. 

When  it  is  necessary  to  place  the  lamps  horizontally,  they  are 
read  from  the  sender's  right  to  his  left,  .and  consequently  from 
the  receiver's  left  to  his  right. 

Example:  red-white,  or  dot-dash,  represents  the*,  letter  A,  and 
white-red-red-red,  or  dash-dot-dot-dot,  represents  the  letter  B. 

For  numerals  in  the  Ardois  system  the  last  ten  letters  have  been 
assigned . for  army  use,  Q  being  1,  R  being  2,. and  so^on,  Z  being  0. 
These  secondary  meanings  apply  only  to  Army  communications ; 
when  communicating  with  the  Navy  the  numerals  of  the  interna- 
tional Morse  Code  must  be  spelled  out  in  full. 

When  letters  of  the  alphabet  are  to  be  used  to  indicate  the  mean- 
ing set  opposite  them  in  the  following  tabulation,  the  upper  light 
of  the  display  is  pulsated.  This  is  effected  by  means  of  a  special 
pulsating  key. 

ARDOIS  SYSTEM  OF  CONVENTIONAL  SIGNALS 

(Used  especially  in  correspondence  with  the  Navy) 

Steady  Upper  light 
Display  pulsated 

A R  W Error 

C W  RW  R Repeat 

H R  R  R  R Execute 

K W  R  W Negative 

L RWRR Preparatory 

N W  R Annulling 

O W   W   W Interrogatory 

P RWWR Affirmative 

Interval RW  RW Designator 

466 


THE  ARDO1S  SYSTEM  467 

Interval  takes  the  place  of  front.  It  is  made  once  for  end  of 
word,  twice  for  end  of  sentence,  and  three  times  for  end  of  mes- 
sage. ^'Designator"  means  that  the  following  signal  designates 
the  call  of  some  ship  or  station. 

NUMERALS — SECONDARY   MEANING 

(Not  to  be  used  in  communicating  with  the  navy) 
Steady  Upper  light 

Display  pulsated 

Q W  W  R  W 1 

R R  W  R 2 

S R  R  R 3 

T W  4 

U R  R  W 5 

V R  RRW 6 

W R  W  W 7 

X WRRW 8 

Y W  RWW 9 

Z W  W  R  R 0 

RULES  FOR  USING  THE  ARDOIS   SYSTEM 

The  general  call  to  attention  is  the  Cornet.  WWW  W. 

A  station  desiring  to  exchange  signals  displays  the  call  letters 
of  the  station  wanted,  which  is  answered  by  a  similar  display  from 
the  station,  or  from  each  station  successively  called. 

When  the  call  letters  of  a  station  are  not  known  the  Cornet  is 
displayed. 

The  call  answered,  the  message  proceeds,  or  if  a  special  or  pre- 
concerted code  is  to  be  used,  it  is  so  indicated  and  acknowledged 
before  the  message  is  begun. 


SIGNALING  BY  TWO-ARM  SEMAPHORE 

The  machine  or  stationary  semaphore  is  authorized  for  general 
use  by  the  Army  at  the  present  time.  This  machine  has  two  arms 
or  vanes  for  forming  signals,  and  a  third  arm  or  '"indicator"  dis- 
played on  the  right  of  the  sender,  the  left  as  viewed  by  the  receiver. 
At  night  a  red  light  screened  to  the  rear  indicates  the  direction  of 
sending.  Electric  lights  are  installed  on  the  vanes  for  night  signal- 
ing. 

Signaling  by  the  two-arm  semaphore  is  the  most  rapid  method  of 
sending  spelled-out  messages.  It  is,  however,  liable  to  error  if  the 
motions  are  slurred  over  or  run  together  in  an  attempt  to  make 
speed.  Both  arms  should  move  rapidly  and  simultaneously,  but 
there  should  be  a  perceptible  pause  at  the  end  of  each  letter  before 
making  the  movements  for  the  next  letter.  Accuracy  is  considered 
far  more  important  than  rapidity  of  operation. 

Communications  with  the  navy  require  numerals  to  be  spelled  out. 
The  alphabet  is  given  in  the  accompanying  plate. 

The  "interval,"  as  shown  on  the  plate,  is  the  machine  closed,  but 
with  the  indicator  showing ;  "double  interval"  is  the  "chop-chop" 
signal  made  twice,  both  arms  being  placed  at  the  right  horizontal 
and  then  moved  up  and  down  in  a  cutting  motion,  the  indicator 
being  displayed.  The  "triple  interval"  is  indicated  by  the  "chop- 
chop"  signal  made  three  times. 

468 


TITO-ARM  SEMAPHORE 


469 


LPF 

4 

CZ 

OR 

* 

<^ 

CZ 

k 

LZ 

j 

CZ 

f 

CZ 

CZ 

A 

1 

B 

2 

c 

3 

D 

4 

E 

5 

F 

6 

I 

CZ 

fc> 

1 

CZ 

CZ 

NEGA 

/} 
</ 

CZ 

rive 

f 

PRE.PAI 

A 

CZ 

VCTOKY 

f 

{ 

i 

CZ 

G 

7 

H 

8 

1 

9 

J 

0 

K 

L 

A 

ANNU 

<5 

L 

5 

JNG 

*> 

INTERROCATY 

AFFIRM 

LATrvE 

f 

f 

ACKNOWLEDGE 

^ 

1 

1 

1 

'LZ 

CZ 

CZ 

CZ 

CZ 

CZ 

M 

N 

o 

p 

Q 

R 

1  — 

*> 

<* 

; 

<^ 

f 

L 

/? 

f 

< 

f 

\ 

CZ 
s 

CZ 
T 

CZ 
u 

CZ 

V 

CZ 
w 

[Z 
X 

^ 

ATTE 

i 

MTION 

SIGNA 

1 

LS 
)LLOW) 

^ 

LETT 

-*£> 

W 

INTEF 

VAU 

x 

r 

CZ 
Y 

CZ 

z 

LZ 

CZ 

LZ 

CZ 

SIGNALING    BY    HAND    FLAGS 

Hand  flags  are  authorized  for  general  use  by  the  Army,  though 
on  account  of  their  small  range  they  are  of  limited  application  and 
are  chiefly  serviceable  for  use  within  organizations,  within  fixed 
positions,  or  for  incidental  signaling.  The  range  with  flags  of  the 
usual  size  is  of  course  dependent  upon  light  and  background,  but 
it  is  seldom  more  than  one  mile  with  the  naked  eye.  This  system 
of  signaling  has  been  highly  developed  in  the  Navy,  and  on  account 
of  its  rapidity  and  simplicity  is  of  use  to  the  Army  and  should  be 
familiar  to  all  soldiers.  It  is  limited  to  visual  signaling  work  and 
not  adapted  to  general  signaling  as  is  the  General  Service  Code. 
It  will  be  found  useful  under  many  circumstances  and  is  adapted 
to  special  work  when  rapid  communication  for  short  distances  is 
needed.  This  method  is  also  used  to  advantage  for  interior  signal- 
ing within  batteries  of  the  field  artillery  and  within  regiments  of 
infantry,  and  at  times  is  convenient  to  the  cavalry. 

The  semaphore  hand  flags  for  service  use  are  18  inches  square 
divided  diagonally  into  two  parts,  one  of  red  and  the  other  of 
white  ;*  the  staffs  are  24  inches  long. 

The  hand  flags  of  the  Navy  are  from  12  to  15  inches  square, 
of  blue  with  a  white  square,  or  red  and  yellow  diagonally,  the  colors 
to  be  used  depending  upon  the  background.  The  flags  are  usually 
attached  to  a  light  wooden  staff  about  two  feet  in  length. 

Hand  flags  are  used  in  the  same  manner  as  the  semaphore  ma- 
chine, except  that  in  making  the  intervals  the  flags  are  crossed 
downward  in  front  of  the  body  (just  above  the  knees)  ;  the  double 
interval  is  the  "chop-chop"  signal  made  twice.  The  triple  interval 
is  the  "chop-chop"  signal  made  three  times,  withdrawing  the  flags 

*  For  the  field  and  the  coast  artillery  there  has  been  temporarily  is.sued 
a  semaphore  hand  flag  of  orange  with  a  scarlet  center  and  scarlet  with  an 
orange  center,  one  of  each  constituting  a  kit.  The  flags  are  18  inches 
square,  the  Centers  9  inches  square,  and  the  staffs  24  inches  long. 

470 


THE   TWO-ARM    SEMAPHdRE    CODE   WITH   HAND    FLAGS 


^ 


00 


471 


472 


MILITARY  SIGNAL  CORPS  MANUAL 


from  view.  In  calling  a  station,  the  signalman  faces  it  squarely  and 
makes  its  call.  If  there  is  no  immediate  reply  he  waves  the  flag 
over  the  head  to  attract  attention,  making  the  call  at  frequent  inter- 
vals. When  the  sender  makes  "end  of  the  message"  the  receiver, 
if  the  message  is  understood,  extends  the  flags  horizontally  and 
waves  them  until  the  sender  does  the  same,  when  both  leave  their 
stations. 


A  PRACTICAL  ILLUSTRATION   OF   TWO- ARM    SEMAPHORE   SIGNAL- 

ING;    A   SIGNAL   MAN    CALLS   "ATTENTION"   TO   INFORM    A 

DISTANT  VISUAL  STATION  THAT  WIRE  CONNECTIONS 

HAVE  BEEN  MADE  WITH  THE  FIRST  REGIMENTAL 

HEADQUARTERS  AND  THE  DIVISION  COMMANDER 


GENERAL  INSTRUCTIONS  FOR  LOCATING  AND  OPERA- 
TING  VISUAL  STATIONS 

The  selection  of  the  site  for  a  visual  signal  station  is  gov- 
erned by  choice  of  a  point  perfectly  in  view  of  the  commu- 
nicating station,  the  exact  position  in  which  the  flagman  is 
to  stand  being  arranged,  if  possible,  so  that  he  will  have  behind 
him  for  every  signal  a  background  of  the  same  color. 


A  PORTABLE  TOWER  CARRIED  BY   FIELD  TROOPS  IN 
SECTIONS  AND  ERECTED  IN  A  FEW  MINUTES, 
PROVIDING  AN  ELEVATION   FOR  OBSERVA- 
TION   AND    VISUAL    SIGNALING 

Secrecy  in  communication  is  vitally  important.  Even  though 
the  code  used  may  not  be  known  to  the  enemy,  the  waving  flag 
or  other  means  of  visual  signaling  will  inform  the  enemy  that 
he  has  probably  been  observed;  stations  should  therefore  be 
located  where  they  will  be  most  difficult  of  discovery.  If  there 

473 


474  MILITARY  SIGNAL  CORPS  MANUAL 

is  reason  to  believe  that  signals  are  seen  by  the  enemy,  they 
should  be  made  in  cipher  and  extraordinary  care  be  taken  in 
transmitting  messages.  Where  practicable,  they  should  be  re- 
peated. 

In  wig-wagging,  the  color  of  the  flag  should  contrast  as 
strongly  as  possible  with  that  of  the  background.  With  green 
or  dark,  or  with  earth-covered  background  the  white  flag 
should  be  used.  The  distant  station  is  the  best  judge  of  back- 
ground, and  it  should  indicate  the  color  of  flag  wanted. 

The  following  table  shows  how  far  an  object  at  sea  level 
can  be  seen : 

Height    of    the    eye    above    sea  Distance  (in 

level  (in  feet)  statute  miles)    . 

10  4 

15  5 

20  6 

30  7 

40  8 

50  9 

60  10 

70  11 

85  12 

100  13 

115  14 

130  15 

150  16 

200  18 

230  20 

300  23 

350  25 

500  30 

700  35 

900  40 

Hence,  an  observer  whose  eye  is  30  feet  above  the  sea  can 
distinguish  an  object  7  miles  distant,  providing  it  is  at  the  sea 
level;  but  if  the  object  itself  is  15  feet  above  the  sea  he  can  make  it 
out  7  +  5  =  12  miles  off. 

In  visual  signaling  over  a  distance  the  telescope  is  used.  In 
locating  the  signalman  at  any  known  station,  some  prominent 
landmark  is  noted  with  the  unaided  eye  and  the  telescope  then 
directed  upon  the  place  and  the  country  near  the  marker  scaled 
until  the  signalman  is  found.  When  the  compass  bearing  is 
known  the  telescope  is  aligned  with  the  proper  compass  bear- 
ing and  the  telescope  moved  slowly  from  side  to  side  until  the 
whole  country  in  that  direction  has  been  scrutinized. 


INSTRUCTIONS  FOR  VISUAL  STATIONS  475 

The  magnetic  bearing  of  all  communicating  visual  stations 
is  always  carefully  noted.  In  addition,  guide  lines  may  be  es- 
tablished by  driving  two  stakes  firmly  into  the  ground  and 
close  to  each  other.  A  line  through  the  center  of  these  should 
point  the  direction  of  the  distant  station.  If  more  than  one 
station  is  being  communicated  with,  the  various  names  should 
be  written  under  the  lines  which  mark  each  one. 

A  signal  officer  should  provide  himself  and  those  working 
under  him  with  the  latest  and  most  accurate  topographic  maps 
of  the  country.  The  location  and  call  letters  of  all  stations  and 
the  personal  signals  of  his  subordinates  should  be  recorded  and 
made  known  to  all  under  his  jurisdiction. 

The  called  station  should  respond  at  once  when  its  particu- 
lar signal  is  shown. 

A  continuous  watch  for  signals  should  be  kept  and  assign- 
ments recorded  so  that  responsibility  for  neglect  to  promptly 
answer  calls  may  be  determined. 

When  a  station  has  sent  all  messages  on  hand,  the  signal 
"Cease  signaling"  should  invariably  be  made.  When  nothing 
more  is  to  be  sent  from  either  station,  both  make  "Cease  sig- 
naling." 

If  a  signal  station  asks  another  to  move  its  station  to  the 
right  or  left,  both  stations  appoint  a  signalman  to  hold  a  flag 
(or  lighted  torch)  above  his  head.  The  station  asking  for  the 
change  lowers  its  flag  immediately  when  the  proper  background 
is  found. 

Attempts  to  attract  the  attention  of  a  station  must  be  per- 
sistent. They  should  never  be  abandoned  until  every  device  has 
been  exhausted,  and  should  be  renewed  and  continued  at  dif- 
ferent hours  of  the  day  and  night. 


LETTER  CODES 

INFANTRY 
For  use  with  General  Service  Code  or  semaphore  hand  flags. 


Letter  of  alphabet 

If  signaled  from  the  rear  to 
the  firing  line 

If    signaled   from    the   firing1 
line  to  the  rear 

A~M 

Ammunition    going    forward 

Ammunition     required 

CCC 

Charge     (mandatory     at     all 

Am    about    to   charge   if   no 

times) 

instructions    to    the    con- 

trary 

CF 

Cease    firing 

Cease  firing 

DT 

Double    time    or    "rush" 

Double  time  or  "rush" 

F 

Commence    firing 

FB 

Fix   bayonets 

FL 

Artillery    fire    is   causing   us 

losses 

G 

Move  forward 

Preparing  to  move  forward 

HHH 

Halt 

K 

Negative 

Negative 

LT 

Left 

Left 

O 

What  is   the   (R  N,   etc.)? 

What  is  the  (R  N,  etc.)? 

(Ardois  and   sem- 

Interrogatory 

Interrogatory 

aphore  only) 

..  —  —•• 

What   is   the   (R  N,   etc.)? 

What   is   the   (R  N,   etc.)  ? 

(All   methods  but 

Interrogatory 

Interrogatory 

ardois  and  sem- 

aphore.) 

P 

Affirmative 

Affirmative 

RN 

Range 

Range 

RT 

Right 

Right 

sss 

Support  going  forward 

Support  heeded 

SUF 

Suspend    firing 

Suspend  firing 

T 

Target 

Target 

CAVALRY 
For  use  with  General  Service  Code  or  semaphore  hand  flags. 

AAA— Ammunition   going   forward   (if  signaled  from   the  rear  to   the   front). 

— Ammunition  required  (if  signaled  from  the  front). 
CCC — Charge  (if  signaled  from  the  rear  to  the  front). 

— About   to   charge,   if  no  instructions  to  contrary  (if  signaled  from  the 
front). 


476 


LETTER   CODES  477 

CF — Cease  firing. 

DT — Double  time,  rush,  or  hurry. 

F — Commence  firing. 

FL — Artillery    fire    is    causing    us    losses. 
G — Move  forward  (if  signaled  from  the  rear  to  the  front). 

— Preparing  to  move  forward   (if  signaled  from  the  front  to  the  rear). 
HHH— Halt. 

K — Negative. 
LT-Left. 
M — Bring  up  the  horses  (if  signaled  from  front  to  rear). 

— Horses  going  forward   (if  signaled  from  rear  to  front). 
O — What  is  the  (R  N,  etc.)?    Interrogatory  (Ardois  and  semaphore  only). 

.. ..  —  What  is  the  (R  N,  etc.)?    Interrogatory  (all  methods  but  Ardois 

and   semaphore). 
P — Affirmative. 
R — Acknowledgment. 
RN— Range. 
RT— Right. 
SSS — Support   going  forsvard   (if   signaled   from   the   rear   to  the   front). 

— Support  needed   (if  signaled  from   the   front  to  the  rear). 
SUF — Suspend  firing. 
T— Target. 


FIELD  ARTILLERY 

For  use  with  General  Service  Code  or  Semaphore  Hand  Flags. 

— Error  (all  methods  but  ardois  and  semaphore). 

A — Error  (ardois  and  semaphore  only). 
AD— Additional. 

AL — Draw  ammunition   from  limbers. 
AKT — Draw  ammunition  from  combat  train. 
AM — Ammunition  going  forward. 
AMC — At  my  command. 

AP — Aiming  point. 

B  (numerals) — Battery  (so  many)  rounds. 
BS  (numerals)— (Such.)    Battalion  station. 
BL— Battery  from  the  left. 
BR— Battery   from   the  right. 
CCC — Charge   (mandatory   at  all   times).    Am  about  to  charge  if 

not    instructed  to   contrary. 
CF — Cease  firing. 
CS — Close  station. 
CT — Change  target. 

D— Down. 
DF— Deflection. 
DT— Double   time.     Rush.     Hurry. 

F — Commence  firing. 

FCL  (numerals)— On  1st  piece  close  by   (so  much). 
FL — Artillery   fire  is   causing  us  losses. 
FOP  (numerals)— On  1st  piece  open  by   (so  much). 

G — Move  forward.     Preparing  to  move  forward. 
HHH — Halt.     Action  suspended. 

IX— Execute.     Go  ahead.    Transmit. 
JI — Report   firing  data. 
K — Negative.     Xo. 
KR — Corrector. 

L — Preparatory.    Attention. 

LCL  (numerals)— On  4th  piece  close  by  (so  much). 
LOP  (numerals)— On  4th  piece  open  bv  (so  much). 
LT-Left. 

LL— Left  from  the  left. 
LR— Left  from  the  right. 
LE  (numerals) — Less  (so  much). 
MD — Move  down. 
ML — Move  to  your  left. 
MR — Move  to  your  right. 
MU — Move  up. 


478  MILITARY  SIGNAL  CORPS  MANUAL 

MO   (numerals) — Move    (so  much). 
N — Annul,  cancel. 

O — What    is    the    (R    N,    etc.)?      Interrogatory.      (Ardois    and 
semaphore  only.) 

.. ..    —What    is   the    (R   N,    etc.)?      Interrogatory.      (All    methods 

but  ardois  and  semaphore.) 
P — Affirmative.    Yes. 
PS — Percussion.    Shrapnel. 
QRQ— Send  faster. 
QRS — Send  slower. 
QRT — Cease  sending. 

R — Acknowledgment.      Received. 
RS— Regimental   station. 
RL— Right  from  the  left. 
RR— Right  from  the  right. 
RN— Range. 
RT— Right. 

S — Subtract.     ' 

SCL  (numerals) — On  2d  piece  close  by   (so  much). 
SOP  (numerals) — On  2d  piece  open  by   (so  much). 
SH— Shell. 
SI— Site. 
SSS — Support  needed. 

T — Target. 

TCL  (numerals) — On  3d  piece  close  by  (so  much). 
TOP  (numerals) — On  3d  piece  open  by  (so  much). 

U— Up. 
Y  (letter)— Such  battery  station. 

COAST  ARTILLERY 

FOR  SHORE-TUG  SIGNALING 

1.  Range  correct,  ready  to  fire K 

2.  Commence  towing  C 

3.  Go  out O 

4.  Come  in 1 

5.  Distress D 

6.  Hold    stationary S 

7.  Turn T 

8.  Incline  to  port L 

9.  Incline  to  starboard R 

10.  Close  practice Z 

EXPLANATION    OF   SHORE-TUG   SIGNALS 

Range  correct,  ready  to  fire — This  signal  is  supplementary  to 
the  firing  signal  displayed  at  the  battery  firing.  At  mortar 
subcaliber  practice  this  signal  may  be  sent  as  each  shot  is  fired. 

Commence  towing— This  signal  means  that  the  towing  vessel 
will  at  once  take  up  the  bearing  course  prescribed.  It  is  under- 
stood that  in  every  case  the  course  on  which  the  target  is  to 
be  towed  is  to  be  indicated  by  compass  bearings  furnished  to 
the  officer  in  charge  of  the  towing  vessel.  By  this  means  it 
will  only  be  necessary  to  get  the  target  on  any  one  point  of 
the  course  and  then  send  the  signal  "commence  towing." 

This  signal  may  be  given  at  any  time,  with  the  towing  vessel 
stationary  or  moving  in  any  direction,  and  means  that  the  vessel 
will  at  once  take  up  the  prescribed  bearing  course. 


SHORE-TUG  SIGNALING  479 

Go  out — This  signal  directs  the  vessel  to  move  straightway 
from  the  battery  firing. 

Come  in — This  signal  directs  the  vessel  to  move  straight 
toward  the  battery  firing. 

Distress — This  signal  sent  by  a  tug  indicates  either  that  the 
tug  is  unable  to  proceed,  due  to  fouling,  breakdown,  shoals,  or 
other  cause ;  or  that,  at  night  practice,  a  shore  searchlight  is 
interfering  with  a  patrol  boat.  After  the  trouble  passes,  Signal 
No.  1  is  given  by  the  tug.  If  the  searchlight  can  not  be  used, 
-distress  signals  should  be  made  by  whistle.  In  any  case,  the 
nature  of  the  trouble  should  be  immediately  communicated  by 
shutter  and  radio,  using  the  General  Service  Code. 

Hold  stationary — This  signal  indicates  that  the  vessel  is  to 
•  lie  to  until  further  orders  are  given. 

Turn — This  signal  indicates  that  the  vessel  is  to  go  about, 
or  make  a  turn  of  180  deg.  If  given  after  No.  6  (hold  stationary), 
it  means  that  the  vessel  will  run  a  course  of  180  deg.  from  that  on 
which  she  was  proceeding  when  No.  6  was  given. 

Incline  to  port. — Given  when  the  vessel  is  on  a  course,  it 
indicates  that  the  vessel  will  incline  to  port  two  points.  Given 
after  No.  6  (hold  stationary),  it  directs  the  vessel  to  run  on 
a  course  two  points  to  starboard  of  that  on  which  she  was  pro- 
ceeding when  No.  6  was  given. 

Close  practice — This  signal  means  that  firing  is  over  for  the 
day  and  that  the  towing  vessel  will  proceed  to  carry  out  such 
special  directions  as  may  have  been  given  relative  to  securing 
and  bringing  in  the  targets. 


TELEGRAPH  CODE  BOOKS  AND  CIPHERS 

Code  books,  which  have  become  familiar  to  all  users  of  the 
telegraph  and  cable  in  ordinary  business  transactions,  are  in- 
tended for  economy  and  to  insure  secrecy.  The  War  Depart- 
ment has  its  official  telegraph  code  adapted  especially  to  mili- 
tary needs,  but  this  is  of  course  available  only  to  those  enlisted 
in  the  service  of  the  Government.  The  training  of  citizen- 
soldiers  in  Signal  Corps  transmission  by  code  need  not  be 
handicapped  by  lack  of  this  equipment,  however,  since  for  pur- 
poses of  familiarizing  themselves  with  the  method  of  employing 
the  code  book,  any  available  telegraph  or  cable  book  may 
be  used. 

When  used  solely  for  economy  the  words  or  phrases  of  the 
message  are  coded  by  direct  reference  to  the  books'  equiva- 
lents— usually  words  of  five  letters  each — and  are  easily  trans- 
lated by  reference  to  the  code  book.  When  secrecy  is  desired, 
however,  some  method  of  enciphering  is  employed  which  can 
be  translated  only  by  those  in  possession  of  the  "key,"  or  the 
secret  of  the  method  of  transcription. 

Ciphers  are  nearly  infinite  in  number  and,  though  probably 
no  one  is  absolutely  unreadable,  the  simplest  cipher  has  the  ad- 
vantage of  delaying  the  reading  of  the  message  should  it  be  in- 
tercepted by  the  enemy.  Another  value  in  the  cipher  is  that  it 
requires  more  or  less  expertness  in  use.  The  Signal  Corps  of 
the  United  States  Army  considers  only  two  cipher  codes  neces- 
sary for  study;  these  are  the  cipher  disk  and  the  route  cipher. 

THE   CIPHER   DISK 

The  cipher  disk  is  the  simple  but  useful  device  pictured  in 
the  accompanying  illustration.  It  is  composed  of  two  circles  of 
cardboard,  celluloid,  or  other  material  joined  through  the  cen- 
ters, the  upper  disk  revolving  on  the  lower.  The  alphabet, 
reading  from  left  to  right,  is  printed  around  the  circumference 
of  the  lower  disk  in  upper  case,  or  capital,  letters.  On  the  up- 
per disk  is  printed  the  alphabet  reading  from  right  to  left,  in 
lower  case,  or  small,  letters. 

480 


CODE  BOOKS  AND   CIPHERS 


481 


When  it  is  desired  to  encipher  a  message,  the  "key"  letter, 
or  the  first  letter  of  the  key  word  or  words,  is  set  opposite  the 
letter  "a."  For  illustration,  assume  it  to  be  "E."  The  cipher  let- 
ters to  be  written  are  those  opposite  the  text  letter  when  the 
letter  "a"  on  the  upper  disk  is  set  opposite  "E"  on  the  lower 
disk.  For  example,  the  message  "Send  powder"  would  be  writ- 
ten "marb  pqiban." 

Numbers  are  spelled  out  when  enciphered  with  the  cipher 
disk. 

In  the  method  of  enciphering  just  described  it  is  obvious 
that  the  mere  transposition  of  letters  would  delay  but  a  short 


THE  CIPHER  DISK  USED  FOR  SECRECY  IN  MESSAGE  TRANSMISSION 

time  the  deciphering,  or  translation,  of  a  message  by  the  enemy, 
even  if  the  key  letter  were  not  known.  It  would  only  be  neces- 
sary to  place,  in  turn,  opposite  "a,"  each  of  the  letters  of  the 
alphabet,  beginning  with  "B"  and  noting  the  letters  until  the 
right  arrangement  made  the  meaning  of  the  message  clear. 

But  when  this  simple  disk  is  used  with  code  book,  or  cipher, 
word  or  words,  known  only  to  the  sender  and  receiver  of  the 
message,  it  is  entirely  improbable  that  the  message  could  be 
deciphered  in  time  to  be  of  any  value  to  the  enemy. 

To  illustrate  the  use  of  key  words  in  this  connection,  we  will 
assume  that  the  key  words  "permanent  body"  are  the  equiva- 


4£!  MILITARY  SJGX.1L  CORPS  M.lXt'.-lL 

lent  cipher  for  the  message :  "Reenforcements  will  reach  you  at 
daylight".  The  procedure  would  then  be  as  follows :  The 
message  would  first  be  written  : 

Reenforcementswillreachyouatday  light 

Then  over  the  message  would  be  written  the  key  words,  let- 
ter over  letter,  thus: 

PERMANENTBODYPERMANENTBODYPERMANENTB 
reenforcementswi 1 Ireachyouatdayl ight 
Now  bring  "a"  of  the  upper  disk  under  the  first  letter  of 
the  key  word  on  the  lower  disk,  in  this  case  "P".  The  first 
letter  of  the  message  to  be  enciphered  is  "R,"  in  the  position 
of  the  disks  at  this  time  "y"  will  be  found  opposite  to  "R",  and 
it  is  put  down  as  the  first  cipher  letter.  The  letter  "a"  is  then 
brought  under  "E",  which  is  the  second  letter  of  the  key  word. 
"E"  is  to  be  enciphered  and  "a"  is  found  to  be  the  second 
cipher  letter.  Then  bring  "a"  to  "R"  and  the  cipher  letter 
"n"  will  represent  'E,"  the  third  text  letter  of  the  message. 
Proceed  in  this  manner  until  the  last  letter  of  the  cipher  words  is 
used,  and,  beginning  again  with  the  letter  "P",  continue  until 
the  entire  message  has  been  enciphered,  letter  by  letter.  The 
result  will  then  be  : 

PERMANENTBODYPERMANENTBODYPERMANENTB 
r  e  e  nforcement  sw  i  1  Ireachyouatdayl  i  ght 
yanzvznlppkqfxi  jbpwanruqpeplomccwhmi 
These  last  letters  will  then  be  divided,  for  convenience  in 
sending,  into  groups  of  five  letters  and  transmitted  thus: 
"yanzv  znlpp  kqfxi  jbpwa  nruqp  eplom  ccwhm  i" 

EMPLOYMENT  OF  THE  CIPHER  DISK 

The  importance  of  using  cipher  words  in  manipulating  the 
disk  to  insure  absolute  secrecy,  over  an  effective  period  of  time, 
is  shown  by  the  ease  with  which  a  message  enciphered  by  the 
mere  transposition  of  the  letters  of  the  alphabet  may  be  quick- 
ly deciphered  by  use  of  the  disk.  This  the  following  message  will 
show : 

Assume  that  "a"  is  used  to  represent  "F,"  "b"  to  represent 
"E,"  "c"  to  represent  "D,"  "d"  to  represent  "C,"  "e"  to  repre- 
sent "B,"  etc.,  in  regular  sequence,  and  the  message  to  be  en- 
ciphered is :  "We  are  short  of  rifle  ammunition  send  20,000 
rounds  at  once." 

This  would  be  enciphered,  if  divided  into  groups  of  five  let- 
ters, as  follows  : 
"jbfob  nyron  raoxa  ubftt  Isxmx  rsnbs  cmjbs  mhmyr  Infsc  orlsc 

nfmrs  db" 
Place  "a"  of  the  upper  cipher  disk  opposite  "B"  of  the  lower 


CODE  BOOKS  AND  CIPHERS  483 

disk  and  notice  whether  the  cipher  letters  "jbfob" — the  first 
group — are  intelligible.  They  give  "SAWNA" ;  continue  this, 
for  "SAW,"  the  first  three  letters  may  be  the  text  word.  Now 
the  next  group  is  "nyrom,"  and  these  give  "ODKNP."  To- 
gether the  first  ten  cipher  letters  give  the  meaningless  letters 
"SAWNAODKNP"  and  we  know  therefore  that  "a"  does  not 
represent  "B."  Turn  "a"  to  "C"  and  we  have  the  first  group 
"TBXOB,"  which  is  without  meaning.  Turning  "a"  to  "D"  we 
get  "UCYPC"  a  meaningless  jumble.  Turn  "a"  to  "E"  and  we 
get  "VDZQD,"  which  is  meaningless.  Now  turn  "a"  to  "F" 
and  we  find  that  "jbfob"  means  "WEARE,"  which  gives  us 
the  two  words  "We  are."  We  continue  with  the  next  group, 
"nyrom,"  which  gives  us  "SHORT."  We  now  have  these  let- 
ters "WEARESHORT,"  which  at  a  glance  we  read  "We  are 
short."  It  would  appear  that  we  have  now  found  the  key  let- 
ter and  after  deciphering  several  additional  groups  we  are  cer- 
tain that  the  information  hidden  in  the  cipher  is  ours.  Con- 
tinue deciphering  with  "a"  opposite  "F"  until  the  end  of  the 
message.  Sometimes  the  key  letter  is  changed  after  two,  three, 
or  four  letters.  It  is  a  matter  of  minutes  only  to  run  through 
the  alphabet  and  learn  the  meaning  of  a  message  so  enciphered. 


IMPROVISED  SUBSTITUTE  FOR  CIPHER  DISK 

Cut  vertical  strips,  each  about  one-half  inch  wide,  from 
lined  writing  paper.  Paste  these  end  to  end  so  that  two  strips 
will  be  made  up,  one  with  26  spaces  and  the  other  with  52 
spaces.  Write  the  alphabet  twice,  beginning  with  letter  "A", 
down  the  52-spaced  strip,  and  write  it  once  backwards,  begin- 
ning with  the  letter  "Z",  down  the  26-spaced  strip.  These  two 
strips,  when  laid  side  by  side,  may  then,  by  sliding  the  26- 
spaced  strip  up  and  down  to  the  appropriate  letter  on  the  52- 
spaced  strip,  be  made  to  perform  the  functions  of  a  cipher  disk. 

THE  ROUTE   CIPHER 

This  is  a  cipher  in  which  the  words  of  a  message  are  re- 
tained unchanged,  but  are  so  disarranged  by  preconcerted 
rules  that  the  sense  becomes  unintelligible.  The  message  as 
received  seems  to  be  a  number  of  disconnected  words  without 
meaning,  but  by  arrangement  in  proper  order  in  accordance 
with  certain  rules  can  be  easily  read.  Messages  enciphered 
in  this  manner  may  be  translated  by  persons  not  in  possession 
of  the  key,  and  therefore  the  information  contained  therein 
should  only  be  of  such  a  character  as  to  be  of  little  value  to  the 
enemy  unless  acted  upon  immediately.  The  usual  method  employed 


484  MILITARY  SIGNAL  CORPS  MANUAL 

by  the  Army  in  arranging  a  message  for  this  cipher  is  to  write 
the  words  in  vertical  columns.  The  number  of  words  in  each 
column  should  always  equal  the  number  of  columns,  being  made 
so,  if  necessary,  by  the  addition  of  sufficient  "blind"  words.  A 
preconcerted  route  is  agreed  upon,  as  up  the  first  column,  down 
the  third,  up  the  second,  etc.  The  message  is  then  transmitted 
without  reference  to  the  columns,  but  is  deciphered  at  the  re- 
ceiving station  by  column  arrangement  and  perusal  along  the 
original  route. 

For  example,  to  encipher  the  message  "Move  daylight. 
Enemy  approaching  from  north.  Prisoners  say  strength  one 
hundred  thousand.  Meet  him  as  planned,"  arrange  as  follows : 

Move  strength  planned  say 

daylight  one  as  prisoners 

enemy  hundred  him  north 

approaching   thousand  meet  from 

Here  the  route  for  translation  is  down  the  first  column, 
up  the  fourth,  down  the  second,  and  up  the  third. 


CONVENTIONAL   AND   PRECONCERTED   SIGNALS   WITH 
ROCKETS,  BOMBS,  SMALL  ARMS,  AND  GUNS 

In  applying  the  dot  and  dash  code  to  rockets,  bombs,  small 
arms,  and  cannon,  use  should  be  made  of  preconcerted  signals, 
or  of  the  International  Code  of  Signals  or  other  conventional  code 
book.  These  signals  are  not  adapted  to  general  use  with  the  dot 
and  dash  code. 

Throughout,  red  may  indicate  a  dot,  white  or  green  a  dash. 
In  cases  where  the  colors  of  signals  are  not  visible,  as  may  be  with 
the  use  of  the  Very  pistol  by  day,  one  may  indicate  a  dot,  two 
fired  simultaneously,  a  dash. 

The  receiving  station  should  promptly  acknowledge  receipt 
of  each  message. 

When  a  line  of  several  stations  is  established,  care  should  be 
taken  that  each  station  is  supplied  with  copies  of  instructions  and 
codes  exactly  alike. 

COSTON   LIGHTS 

These  lights  are  made  of  a  slow-burning  composition  and  are 
usually  held  in  a  socket  and  displayed  by  hand. 


Rockets  used  by  the  Army  are  of  two  kinds,  YIZ,  sequence 
rockets,  showing  red  and  white  stars,  and  yellow-smoke  rockets. 
With  the  sequence  rockets  there  is  included  a  dummy  element. 
These  rockets  are  packed  in  water-tight  cases  and  are  plainly 
labeled. 

BOMBS 

Bombs  used  by  the  Army  are  of  two  kinds,  white  or  red  for 
night  use  and  smoke  bombs  for  day  use.  They,  like  rocket  signals, 
are  not  adapted  for  general  use  with  the  dot-and-dash  code,  but 
should  be  used  with  preconcerted  signals,  or  to  indicate  letters  of 
the  International  Code  of  Signals  or  other  conventional  code  book. 

485 


486  MILITARY  SIGXAL  CORPS  .U.-OT.-I7- 

Like  rockets  for  night  signaling,  the  red  bomb  indicates  a  dot,  the 
white  a  dash. 

VERY  "PISTOL 

The  Very  system  is  used  by  the  Navy  only  to  transmit  flag- 
code  signals  contained  in  the  Battle  or  General  Signal  Book. 

The  Very  pistol  is  a  breech-loading,  single-shot  pistol,  with 
an  8-inch  steel  barrel  chambered  to  receive  a  12-gauge  commercial 
shotgun  shell.  Brass  shells  are  used,  and  are  packed  in  boxes 
colored  to  indicate  an  element  of  any  alphabet  or  any  special  signal 
which  may  be  desired.  The  stars  rise  to  a  height  of  about  200  feet 
and  remain  visible  for  some  time. 

The  Very  pistol  projects  red,  white,  and  green  stars  for  use  at 
night  and  the  streamer  of  smoke  for  use  in  daytime.  The  stars 
can  readily  be  seen  several  miles  at  night,  and  the  smoke  streamer 
can  be  picked  up  by  glasses  for  over  a  mile  in  daytime. 

In  making  a  signal  the  stars  are  projected  deliberately,  one  by 
one,  from  the  first  to  the  last,  without  regard  to  time  intervals. 
It  is  desirable,  however,  that  the  stars  should  be  projected  ver- 
tically or  so  as  to  fall  in  the  direction  of  the  receiver  of  the  message, 
and  that  they  should  appear  without  very  unequal  intervals  be- 
tween them ;  at  the  same  time,  through  some  unforseen  cause,  a 
long  interval  may  elapse  between  two  stars  of  a  message,  but  no 
account  of  this  shall  be  taken  unless  the  interval  is  prolonged  to 
about  a  minute. 

A  star  may  be  broken  by  the  shock  of  discharge  and  show  several 
stars  of  the  same  color  in  the  air.  This  will  be  recorded  as  one 
star. 

When,  after  waiting  about  one  minute,  the  receiver  of  the  signal 
sees  no  more  signal  stars,  he  will  consider  the  signal  finished. 

SOUND    SIGNALS1 

Sound  signals  made  by  the  whistle,  foghorn,  bugle,  trumpet, 
and  drum  may  well  be  used  in  a  fog,  mist,  falling  snow,  or  at  night. 
They  may  be  used  with  the  dot  and  dash  code. 

In  applying  the  General  Service  Code  to  whistle,  foghorn, 
bugle,  or  trumpet,  one  short  blast  indicates  a  dot  and  one  long 
blast  a  dash.  With  the  drum,  one  tap  indicates  a  dot  and  two 
taps  in  rapid  succession  a  dash.  Although  these  signals  can  be 
used  with  a  dot-and-dash  code,  they  should  be  so  used  in  connec- 
tion with  a  preconcerted  or  conventional  code. 

With  small  arms,  field,  siege,  or  seacoast  guns,  one  shot  may 
indicate  a  dot,  two  shots  a  dash ;  but  in  this  case  the  signals 
are  not  adapted  to  the  general  use  of  a  dot-and-dash  code,  but 
should  be  employed  in  connection  with  a  preconcerted  or  conven- 
tional code. 

1See  also  Emergency   signals. 


FLAG  SIGNALS  BY  PERMANENT  HOIST 

INTERNATIONAL   CODE 

The  term  "flag  signals"  or  "flag  code  signals,"  as  used  by 
the  Navy,  applies  to  signals  made  by  hoists  of  flags,  and  should  not 
be  confused  with  the  use  of  the  expression  by  the  Army  to  indicate 
what  is  known  to  the  Navy  as  wigwag  signals. 

The  only  flag  signals  by  permanent  hoist  and  corresponding 
code  books  authorized  for  use  by  the  Army  are  the  International 
Code  of  Signals  and  Code  List  of  American  Vessels. 

The  International  Code  of  Signals  will  be  used  by  the  Army 
when  such  use  may  appear  desirable,  as  on  Army  transports  and  at 
seacoast  fortifications,  and  between  the  Army  and  Navy,  in  accord- 
ance with  recommendations  of  the  Army  and  Navy  Board.  Sets  of 
International  Code  Flags,  the  International  Code  of  Signals,  and 
the  Code  List  of  American  Vessels  will  be  issued  by  the  Signal 
Corps  in  cases  where  the  application  therefor  is  approved  by 
proper  authority. 

The  International  Code  of  Signals  consists  of  26  flags — 
one  for  each  letter  of  the  alphabet — and  a  code  pennant.  The 
flags  are  used  in  connection  with  the  International  Code  Book 
of  Signals.  Explanation  for  the  proper  use  of  this  code  is  given 
in  the  Code  Book. 

Night  signals  to  boats  will  be  made  by  the  two-arm  sema- 
phore, torch,  portable  lantern,  or  electric  system  in  the  same 
manner  as  other  signals  of  the  Navy.  In  the  Navy  the  Very 
system  is  not  contemplated  for  signaling  to  boats,  being  too 
cumbersome.  The  electric  system  used  should  be  either  the 
Ardois  or  the  blinker,  using  the  dot-and-dash  code  for  either. 
It  is  provided  that  boats  shall  acknowledge  by  day  with  the 
Navy  code  hand  answering  pennant,  and  by  night  with  a  hand 
lantern  or  torch  or  Very's  red  star. 

Code  List 

The  Code  List  of  American  Vessels  is  a  publication  of  the 
Bureau  of  Navigation,  Department  of  Commerce,  setting  forth 
the  names  of  United  States  vessels,  their  flags,  signal  letters, 
official  numbers,  etc. 

The  General  Signal  Book  of  the  Navy,  being  confidential, 
will  not  be  issued  to  or  used  by  the  Army. 

Codes  to  be  used  with  rockets,  bombs,  etc.,  are  not  specific- 
ally included  in  the  system  agreed  upon  for  use  between  the 
Army  and  Navy.  They  are  not  prescribed  for  use  by  the  Navy. 

The  International  Code  of  Signals,  List  of  Radio  Telegraph 
Stations  of  the  World,  and  the  Code  List  of  American  Vessels, 
with  the  proper  code  flags,  will  be  kept  on  hand  at  radio  or 
other  coastal  stations  of  the  Army  where  authorized. 

487 


EMERGENCY  SIGNALS 

In  the  Army  special  emergency  signals  are  authorized  for. 
use  when  circumstances  permit  and  conditions  justify  their 
authorization  by  officers  in  command. 

They  are  given  here  only  as  information  which  may  be  of 
value  in  time  of  national  emergency.  Under  no  condition  are 
they  to  be  used  by  the  citizen  soldier,  or  their  use  authorized 
by  commanding  officers  of  troops  not  regularly  enlisted  in 
the  Army. 

These  signals  are  designed  to  secure  the  attention  of  per- 
sons within  their  radius ;  they  may  indicate  distress ;  ask  as- 
sistance;  give  a  general  alarm  in  case  of  riot,  attack,  flood, 
or  conflagration,  or  other  urgent  reasons. 

EMERGENCY  CABLE  AND  TELEGRAPH  SIGNALS 

The  emergency  signal  for  use  on  cable  or  land  telegraph 
lines  is  the  numeral  "9." 

EMERGENCY   SIGNALS   FOR   RADIOTELEGRAPH Y 

The  radio  distress  signal  for  use  at  sea  is  the  international 
signal  SOS.  An  Army  operator  aboard  ship,  upon  receiving 
an  SOS  signal,  immediately  ascertains  the  exact  position,  in 
latitude  and  longitude,  of  the  vessel  sending  the  signal  and 
delivers  the  information  to  the  officer  in  charge  of  the  ship. 

SIGNALS  OF  DISTRESS  ox  ARMY  TRANSPORTS 

The  signals  of  distress,  used  either  together  or  separately, 
on  Army  transports  are  as  follows: 

In  the  daytime  : — 

First.  A  gun  or  other  explosive  signal  fired  at  intervals  of 
about  one  minute. 

Second.  The  International  Code  signal  of  distress  indicated 
by  NC 

488 


EMERGENCY  SIGNALS  489 

Third.  The  distance  signal,  consisting  of  a  square  flag  hav- 
ing either  above  or  below  it  a  ball  or  anything  resembling 
a  ball. 

Fourth.  A  continuous  sounding  with  any  fog  signal  appara- 
tus. 

At  night  :— 

First.  A  gun  or  other  explosive  signal  fired  at  intervals  of 
about  a  minute.  , 

Second.  Flames  on  the  vessel  (as  from  a  burning  tar  bar- 
rel, oil  barrel,  etc.) 

Third.  Rockets  or  shells  throwing  standard  Army  transport 
night  signals,  fired  one  at  a  time,  at  short  intervals. 

Fourth.  A  continuous  sounding  with  any  fog  signal  appara- 
tus. 

These  signals  require  no  answer,  but  any  station  hearing 
or  seeing  them  is  expected  to  make  every  effort  to  assist  the 
ship  in  distress. 

On  Army  transports  the  fire  signal  is  the  continuous  and 
rapid  ringing  of  the  ship's  bell  for  a  period  of  not  less  than  20 
seconds.  This  signal  is  not  used  for  any  other  purpose  what- 
soever. 

EMERGENCY   SIGNALS  WITH   BOMBS,   SMALL  ARMS,  OR  THE 
NATIONAL   ENSIGN 

A  general  attention  or  alarm  signal  is  indicated  by  one 
discharge  of  a  cannon,  rifle,  pistol,  or  smoke  bomb  by  day. 
followed  by  a  smoke  rocket  at  half-minute  intervals.  At  night, 
by  one  discharge  of  cannon,  small  arm,  or  light  bomb,  fol- 
lowed by  a  red  rocket  at  half-minute  intervals.  This  signal 
requires  no  answer.  Used  as  an  emergency  signal  it  calls  all 
troops  to  attention,  the  smoke  bomb  followed  by  a  rocket 
indicating  riot  or  attack  and  requiring  troops  to  fall  into  ranks 
under  arms.  Should  the  first  rocket  be  followed  by  a  second, 
the  signal  indicates  a  conflagration  or  other  danger,  and 
troops  fall  into  ranks  prepared  to  fight  fire  or  meet  other 
danger,  such  as  flood. 

When  no  bombs  or  rockets  are  at  hand  the  general-alarm 
signal  is  made  by  a  rapid  discharge  of  shots. 

With  the  national  flag,  the  universally  understood  distress 
signal  is  made  by  flying  the  ensign  union  down. 

The  long  roll  of  the  drum  is  also  recognized  in  the  Army 
as  a  general-alarm  signal  and  requires  all  troops  to  fall  into 
ranks. 


CONVENTIONAL  TELEPHONE  SIGNALS 

There  are  certain  letters  of  the  alphabet  which  are  at  times 
confused  with  other  letters  of  similar  sound.  Such  is  particu- 
larly true  when  using  the  telephone.  This  condition  gives  rise 
to  delays  and  errors,  especially  when  transmitting  cipher. 

To  provide  a  ready  means  of  phonetically  distinguishing 
similar  sounding  letters,  the  following  is  authorized: 

A— Able  N— Nan 

B— Boy  O— Opal 

C— Cast  P— Pup 

D— Dock  Q— Quack 

E — Easy      .  R — Rush 

F — Fox  S — Sail 

G — George  T — Tare 

H— Have  U— Unit 

I— Item  V— Vice 

J— Jig  W— Watch 

K— King  X— X-ray 

L— Love  Y— Yoke 

M— Mike  Z— Zed 

,  Example:  If  the  operator  receives  "buy"  as  "vie,"  and  diffi- 
culty is  experienced  in  distinguishing  "B"  from  "V,"  "buy"  may 
be  spelled  "boy-u-y." 


490 


PART  V— FIELD  SERVICE 


SIGNAL  TROOPS  IN  THE  FIELD 

In  defining  the  exact  duties  of  Signal  Corps  in  the  field  it  may 
be  said  that  it  exists  for  the  speedy  dissemination  of  military 
information.  It  is  the  nerve  system  of  the  army  by  which  in- 
formation is  transmitted  to  the  brain.  Unlike  other  branches  of 
the  service  there  are  no  fixed  rules  for  its  operation  which  could 
be  condensed  into  a  tactical  manual  such  as  exists  for  other  fighting 
units. 

An  official  bulletin  from  the  office  of  the  chief  of  staff,  U.  S. 
Army,  deals  with  conditions  in  field  service  by  stating  that  the 
Signal  Corps  is  specially  organized,  trained,  and  equipped  for  the 
collection  and  transmission  of  military  information,  and  only  the 
most  general  instructions  should  be  given  to  officers  and  men  as 
to  the  manner  of  performing  their  duties.  It  is  inadvisable, 
especially  in  brief  field  orders,  to  attempt  detailed  instructions ; 
it  will  suffice  in  such  orders  to  state  the  commands  to  be  joined, 
their  location,  and  a  broad  statement  of  the  object  desired.  It  is 
assumed  that  the  signal  officer,  acting  under  his  general  instructions 
and  the  orders  of  his  immediate  commander,  possesses  the  knowl- 
edge, the  initiative,  and  the  energy  to  meet  conditions  as  they  arise. 

The  signal  officer  at  headquarters,  in  addition  to  caring  for 
the  technical  administration  and  supply  of  the  signal  troops,  will 
keep  himself  informed  as  to  the  location  of  commands,  the  time 
and  character  of  projected  movements;  in  short,  regarding  all 
actual  and  probable  happenings,  so  that  he  may  make  due  pro- 
vision in  advance.  He  must  arrange  for  the  prompt  transmission 
of  information  received,  and  for  the  delivery  of  all  messages. 
He  also  makes  certain  that  the  military  intelligence  contained 
in  messages  to  the  commanding  general  and  chief  of  staff  is 
properly  recorded  on  the  map  or  otherwise  graphically  so  as 
to  be  instantly  available,  and  for  this  purpose  should  establish 
a  central  station  at  division  headquarters,  equipped  to  properly 
file  all  messages  sent  and  received,  in  chronological  order  and 
by  organizations.  This  station  should  also  be  able  to  furnish 
at  all  times  exact  information,  as  to  signal  stations  and  location 
of  troops. 

491 


492 


MILITARY  SIGNAL  CORPS  MANUAL 


The  commander,  aided  by  his  chief  signal  officer,  must  plan 
and  direct,  but  the  signal  officers  and  the  men  under  them 
must  execute:  on  their  energy  and  ability  will  depend  the  value 
and  success  of  the  lines  of  information. 


ESTABLISHING  LINES  OF  INFORMATION — THE  DIVISION 

Since  the  Signal  Corps  is  considered  as  auxiliary  troops  at- 
tached to  a  division  it  is  best  to  define  its  field  duties  in  this 
connection.  While  definite  rules  cannot  be  laid  down  for  the 


TYPE  OF  RADIO  TRACTOR  WHICH  TRAVELS  WITH  DIVISION 
HEADQUARTERS   AND   IS   FIRST   PUT    IN   COMMISSION 

establishment  of  lines  of  information  for  a  division  in  the  field, 
there  are  certain  fundamental  considerations  or  general  prin- 
ciples to  be  observed. 

The  division  may  be  considered  under  three  conditions  :  in 
camp,  on  the  march,  and  in  contact  with  the  enemy. 

When  a  division  is  to  be  assembled  in  a  certain  locality  and 
camp  established,  an  officer  is  sent  ahead  to  select  sites  for  the 
encampment  of  the  various  units  of  infantry,  cavalry  and  ar- 


SIGNAL  TROOPS  IN  THE  FIELD  493 

tillery.  Quartermaster  officers  locate  their  depots  and  medical 
officers  the  field  hospitals.  It  is  then  the  duty  of  the  signal  of- 
ficer to  proceed  with  the  installation  of  lines  of  information. 

A  wireless,  or  radio  set,  of  the  cart  or  tractor  type  travels 
with  division,  corps  and  army  headquarters  and  is  first  put  in 
commission.  A  central  station  is  next  established  at  division 
headquarters  and  connected  with  the  most  convenient  tele- 
graph and  telephone  offices  through  which  communication  may 
be  established  with  commercial  systems  or  the  base. 

The  Signal  Corps  camp  is  then  established  with  a  depot  for 
storing  all  material  needed  for  the  service  to  be  required.  Corps 
or  army  headquarters  are  connected  by  wire  or  radio,  telephone 
lines  carried  to  the  chief  quartermaster  and  surgeon  and  the 
various  hospitals,  depots,  and  corrals. 

The  object  to  be  attained  is  the  connection  of  every  im- 
portant point  with  division  headquarters,  to  link  the  whole 
command  together  and  connect  with  the  base  by  wire  or  radio. 
As  the  various  units  arrive  at  their  camps,  telephone  or  buzzer 
lines  are  run  from  division  central  to  brigade  headquarters, 
through  regimental  to  battalion  headquarters. 

Between  fixed  stations  within  the  limits  of  the  divisional 
camp  the  telephone  is  the  ordinary  means  of  communication, 
telegraph  and  radio  being  reserved  for  more  distant  work. 
Telephone  and  telegraph  lines  are  usually  carried  by  lances. 
In  addition  to  the  more  permanent  lines,  temporary  buzzer  or 
field  wires  are  usually  laid  to  changing  positions,  such  as  out- 
lying observation  points,  to  the  outposts  and  to  aero  stations. 

In  camp  there  should  be  little  difficulty  in  using  fully  the 
lines  of  information,  since  the  extent  and  direction  of  the  sys- 
tem are  known  and  the  stations  are  easily  found  On  the 
march,  however,  the  lines  of  information  become  fewer  and  the 
stations  more  difficult  to  reach.  Some  general  considerations 
may  be  noted. 

A  division  on  the  march  must  at  no  time  lose  electrical  con- 
nection with  its  base,  through  the  last  station  occupied,  and  for 
this  purpose  the  pack  radio  is  especially  useful.  As  the  advance 
continues  the  commanding  general  designates  some  position  as 
his  own  during  the  day  or  night  and  lines  are  extended  for- 
ward or  communication  is  maintained  by  radio  with  this  posi- 
tion, it  becoming,  so  far  as  the  lines  of  information  are  con- 
cerned, the  headquarters. 

As  radio  stations,  the  buzzer,  or  field  wire  advance  they 
should  be  followed,  if  practical,  by  the  telegraph  train  with  the 
necessary  material  for  a  lance  line  to  replace  the  field  or  buz- 
zer wire,  which,  if  exposed,  is  liable  to  injury  from  passing 
troops  and  transport.  At  times,  with  good  roads  and  open 


494 


MILITARY  SIGNAL  CORPS  MANUAL 


country  the  advance  is  so  rapid  where  a  lance  line  is  being 
erected  by  trained  men,  that  little,  if  any,  cable  need  be  used 
on  the  march.  Buzzer  wire  may  follow  the  general  line  of  ad- 
vance of  the  commander  by  extending  from  one  conspicuous 
station  to  another  designated  by  him.  The  field  line,  or  ra- 
dio, is  used  only  for  rapid  work.  Radio,  when  used  on  the 
march,  is  advanced  by  the  leap-frog  method;  that  is,  three  sec- 
tions are  used,  the  rear  station  passing  the  two  preceding  and 
thus  constantly  maintaining  two  stations  in  operation. 


A  FOREIGN   FIELD  WIRELESS  STATION  OF  THE  CART  TYPE    USING 

TWO   MASTS   AND    HORIZONTAL    AERIAL    WITH 

WIRE   MATTING   COUNTERPOISE 

In  the  advance  the  units  of  a  command  should,  so  far  as 
possible.be  kept  in  touch  with  each  other  ;  but  as  these  units  fre- 
quently move  by  different  routes,  and  as  cross  lines  are  im- 
practicable except  at  halts,  field  or  buzzer  wires  must  stretch 
from  the  last  field  station  maintained  at  the  rear  to  corps 
headquarters  and  to  brigade  and  to  important  commands,  as 


SIGNAL  TROOPS  IN  THE  FIELD  495 

the  ribs  of  a  fan  expand;  here,  too,  the  radio  may  best  be  used. 
If  possible,  wire  communication  between  the  general  and  de- 
tached commands,  or  cavalry  at  the  flanks,  is  also  maintained 
in  this  way,  or  communication  established  by  means  of 
visual  signaling  or  radio.  Visual  signaling  may  be  used  to  ad- 
vantage during  halts  when  wire  lines  can  quickly  be  thrown 
out;  and  radio,  especially  of  the  wheel  type,  is  particularly 
useful. 

When  the  day's  march  is  over  and  the  division  eats  and 
rests,  the  work  of  the  signal  men  begins  anew.  Radio  stations 
must  be  established  and  buzzer  lines  run  from  the  advance 
guard,  from  the  flank,  from  the  corps  headquarters,  and  from 
the  rear  to  division  headquarters,  and  still  others  laid  out  as 
already  described  in  a  preceding  paragraph. 

When  a  retiring  movement  is  begun  the  lines  of  informa-- 
tion  are  as  few  as  possible  and  mainly  used  to  connect  the 
rear  guard,  probably  by  radio,  with  the  general  commander. 
Provision  is  made,  however,  to  recall  the  flanking  parties 
thrown  out  at  intersecting  roads  when  the  rear  of  the  march- 
ing columns  pass.  It  is  well  also  to  connect  retreating  col- 
umns moving  by  different  roads,  and  this  can  be  done  by  wire 
and  radio  more  readily  than  in  the  advance,  since  lines  ex- 
tending to  the  front  of  the  retreating  force  will  not  ordinarily 
be  in  danger  of  interruption.  In  the  retreat,  therefore,  cen- 
tral stations  may  be  thrown  out  far  ahead  and  wires  led  back 
like  the  ribs  of  a  fan  to  the  marching  column,  as  in  the  ad- 
vance, to  be  taken  up  as  the  columns  pass. 

As  the  period  of  actual  contact  with  the  enemy  approaches 
the  most  serious  of  the  problems  of  the  lines  of  information 
arise.  The  general  commanding  must  know  the  terrain  and  the 
best  means  of  sending  messages  across  it ;  he  must  know  the 
probability  of  success  of  the  attempts  of  the  enemy  to  cut  the 
wires,  or  "jam"  a  radio,  and  it  is  when  difficulties  arise  that 
every  possible  means  of  signaling  that  offers  a  chance  of  suc- 
cess is  employed. 

As  the  division  approaches  the  enemy,  the  commander  makes 
as  certain  as  possible  that  his  lines  of  information  with  corps 
and  army  headquarters,  with  supporting  and  reserve  troops, 
and  with  the  fear,  are  in  order  and  when  actual  contact  comes, 
buzzer  lines  will  be  carried  to  brigades,  to  regiments,  and  some 
times  to  the  outposts.  For  the  troops  engaged,  buzzer  lines 
are  carried  forward  to  the  firing  line,  where  trained  observers 
with  buzzers  or  the  field  telephone  are  placed  to  send  back  im- 
portant information  for  control  of  fire. 

It  may  be  practicable  at  the  beginning  of  the  action  to 
maintain  touch  by  radio  or  even  by  wire  between  the  smaller 


496 


MILITARY  SIGXAL  CORPS  MAXTAL 


reserves,  the  supports,  and  the  main  bodies,  but  the  latter  is 
doubtful,  since  a  great  multiplicity  of  wires  on  the  field  of 
battle  is  hazardous. 

When  the  division  is  actually  engaged  against  the  enemy 
the  commander  extends  his  field  or  buzzer  line  to  the  posi- 
tions occupied  by  the  infantry  and  artillery  commands.  Radio 
is  in  general  depended  upon  to  keep  him  in  touch  with  his 
cavalry.  The  artillery,  in  addition  to  its  other  lines  of  infor- 
mation, establishes  between  batteries  a  system  of  fire  control, 
the  information  being  transmitted  from  fixed  stations,  cap- 
tive balloons  or  airplanes,  by  radio,  field  telephone  or  buzzer, 
or  by  visual  signals. 

The  radio  is  of  greatest  importance  in  the  field  and  especial- 
ly when  used  at  the  larger  headquarters.  Together  with  the 
increasingly  greater  use  of  the  field  telephone  in  directing  the 
fire  of  heavy  artillery,  the  large  scope  of  the  tactical  require- 
ments in  modern  warfare  has  enormously  increased  the  ^vork 
of  the  Signal  Corps. 

Communication  problems  are  easier  with  the  smaller  bodies 
of  troops,  but  not  less  important.  When  operating  in  an 
enemy's  country,  especially  if  the  movements  are  connected 
with  a  boat  expedition  or  with  the  navy,  somewhat  less  weight 
must  be  given  to  wire  communications,  and  more  reliance  be 
placed  upon  visual  signaling  and  on  the  portable  radio  units. 
With  all  such  expeditions  the  field  acetylene  lantern  is  ex- 
tremely useful,  for  its  range  under  favorable  conditions  is 
easily  20  miles,  and  it  can  be  used  by  hand  from  a  boat  if  on 
quiet  water. 


THE    HEADQUARTERS    WIRELESS    SET    ESTABLISHED    BY    THE 
JUNIOR  AMERICAN  GUARD  FOR  ITS  SEMI-PERMANENT  CAMP 


RECONNAISSANCE,  PATROLLING  AND  SCOUTING 

A  patrol  is  a  small  body  of  infantry  or  cavalry  sent  out  from 
the  command  at  any  time  to  secure  information  of  the  enemy  and 
of  the  country,  also  to  drive  off  small  hostile  bodies  bent  upon 
observing  forces,  or  blowing  up  bridges  or  destroying  railroad 
tracks. 

The  size  of  a  patrol  depends  upon  its  mission;  if  it  is  to  gain 
information  only  it  is  made  as  small  as  possible,  allowing  two  men 
for  each  probable  message  to  be  sent. 

Patrol  leaders,  usually  non-commissioned  officers,  are  selected 
for  their  endurance,  keen  eyesight,  ability  to  think  quickly  and 
good  military  judgment.  A  patrol  leader  should  be  able  to  read 
a  map,  make  a  sketch  and  send  messages  that  are  easily  under- 
stood. The  leader  should  have  a  map,  watch,  field  glass,  compass, 
message  blank  and  pencil. 

It  is  often  said  that  more  battles  are  lost  through  lack  of  in- 
formation about  the  enemy  than  from  any  other  cause,  and  it  is 
the  patrols  led  by  non-commissioned  officers  who  must  gather  al- 
most all  this  information.  A  battalion  or  a  squadron  stands  a 
very  good  chance  of  defeating  a  regiment  if  the  battalion  com- 
mander knows  all  about  the  size,  position  and  movements  of  the 
regiment  and  his  adversary  knows  but  little  about  the  battalion. 

Patrols  are  usually  sent  out  from  the  advance  party  of  an  ad- 
vance guard,  the  rear  party  of  a  rear  guard,  the  outguards  of  an 
outpost  and  the  flank  (extreme  right  or  left)  sections,  companies 
or  troops  of  a  force,  but  they  may  be  sent  out  from  any  part  of 
the  command. 

It  is  of  the  greatest  importance  for  Signal  Corps  men  to  trans- 
mit to  commanding  officers  with  accuracy  and  dispatch  the  infor- 
mation secured  by  the  patrols.  A  signalman  is  made  doubly  efficient 
by  the  possession  of  knowledge  required  for  successful  recon- 
naissance. 

497 


498 


MILITARY  SIGXAL  fOXPS  MANUAL 


ORDERS     OR     INSTRUCTIONS 

The    orders    or    instructions    for    a    patrol    must    state    clearly, 
v/henever  possible : 

1.  Where  the  enemy  is  or  is  supposed  to  be. 

2.  Where  friendly  patrols  or  detachments   are  apt  to  be 

seen  or  encountered  and  what  the  plans  are  for  the 
body  from  which  the  patrol  is  sent  out. 

3.  What     object     the     patrol     is     sent     out     to     accomplish; 

what  information  is  desired;  what  features  are  of 
especial  importance:  the  general  direction  to  be  fol- 
lowed and  how  long  to  stay  out  in  case  the  enemy  is 
not  met. 

4.  Where  reports  are  to  be  sent. 


A  QUICK  RELAY  OF  INFORMATION  BROUGHT  IN 
BY  A  SCOUT  PATROL 


RECONNAISSANCE  499 

MESSAGES 

The  skillful  patrol  leader  is  particularly  adept  in  preparing 
his  information  for  transmission ;  he  fully  understands  when 
to  send  a  message  and  how  to  write  it. 

Messages  should  be  short  and  clear,  resembling  a  telegram. 
If  the  accounts  are  long,  it  takes  too  much  time  to  write  them 
and  they  may  be  easily  misunderstood. 

The  essential  information  invariably  includes  when  and 
where  things  are  seen  or  reported.  If  haste  is  required  valu- 
able moments  should  not  be  lost  in  writing  down  the  day  of 
the  month  and  minor  details.  While  data  of  this  type  is  essen- 
tial as  a  matter  of  future  reference  for  formal  messages  it  may 
be  left  out  if  its  inclusion  should  mean  slighting  the  essential 
points  of  information  of  great  value  to  the  commanding  officer. 

The  exact  location  of  the  enemy  should  be  stated;  also 
whether  deployed,  marching  or  in  camp;  the  strength,  whether 
cavalry,  infantry  or  artillery,  in  fact  full  details  of  the  infor- 
mation secured.  Locations  are  given  by  direction  and  distance 
from  some  point  which  the  commanding  officer  in  the  rear  has 
knowledge  of ;  reference  should  not  be  made  to  houses  or 
streets  which  he  probably  knows  nothing  of. 

It  is  essential  that  messages  be  accurate.  Information  given 
should  not  be  reported  as  a  fact,  but  as  a  statement  made  by 
somebody  else;  particulars  regarding  the  informant  are  often 
added,  such  as  his  apparent  honesty  and  the  probabilty  of  his 
information  being  correct. 

Messages  from  patrol  leaders  always  end  with  a  short  state- 
ment of  what  he  is  going  to  do  next.  For  example:  "will  re- 
main in  observation,"  "will  continue  north,"  "will  work  around 
to  their  rear." 

It  is  frequently  just  as  important  to  send  messages  that  the 
enemy  is  not  in  a  certain  locality  as  it  is  to  report  his  actual 
whereabouts. 

HOW    INFORMATION    IS    SECURED 

The  patrol  leader  always  tnes  to  discover  if  one  hostile 
detachment  is  followed  by  another;  that  is,  if  what  can  be 
seen  appears  to  be  an  advance  guard  of  a  larger  body  not  yet 
in  view.  The  distance  between  the  detachments  and  their  rela- 
tive size  is  always  important. 

The  strength  of  a  column  may  be  estimated  from  the  length 
of  time  it  takes  to  pass  a  selected  point.  An  infantry  in  column 
of  squads  occupies  half  a  yard  per  man,  cavalry  one  yard  per 
horse,  and  artillery  in  single  file  twenty  yards  per  gun  or  cavs- 


500  MILITARY  SIGNAL  CORPS  MANUAL 

son  (ammunition  wagon),  a  selected  point  would  be  passed  in 
one  minute  by  175  infantry;  110  cavalry  at  a  walk;  200  cavalry 
at  a  trot  and  five  guns  or  caissons.  Half  of  these  figures  are 
taken  if  the  force  is  marching  in  column  of  twos. 

The  direction  of  march  and  composition  of  a  column,  whether 
infantry,  ca'valry  or  artillery,  can  be  estimated  from  the  length 
and  character  of  the  cloud  of  dust  it  makes.  Dust  from  in- 
fantry hangs  low ;  from  cavalry  it  is  higher,  disperses  more 
quickly,  and  if  the  cavalry  moves  rapidly,  the  upper  part  of 
the  cloud  is  thinner;  from  artillery  and  wagons,  it  is  of  un- 
equal height  and  disconnected.  The  effect  of  the  wind  blowing 
the  dust  must  be  considered. 

The  trail  of  a  column  also  leaves  significant  signs.  Evenly 
trodden  ground  indicates  infantry;  prints  of  horseshoes  mean 
cavalry,  and  deep  and  wide  wheel-tracks  indicate  artillery.  If 
the  trail  is  fresh,  the  column  passed  recently;  if  broad  they 
expected  an  action  and  were  prepared  to  deploy.  A  retreating 
force  makes  a  broad  trail,  especially  at  the  start. 

The  smallest  or  most  insignificant  things,  such  as  the  num- 
ber of  a  regiment  on  a  discarded  canteen  or  collar  ornament, 
may  give  the  most  valuable  information  to  a  higher  com- 
mander. For  example,  these  markings  might  prove  to  a  field 
general  that  a  certain  hostile  division,  corps,  or  other  force, 
was  in  front  of  him  when  he  thought  it  had  not  been  sent  into 
the  field. 

If  the  reflection  of  weapons  is  brilliant  the  troops  are  march- 
ing toward  the  observer,  otherwise  they  are  probably  marching 
away  from  him. 

Camp  noises,  such  as  the  rumble  of  vehicles,  cracking  whips, 
neighing  horses,  braying  mules  and  barking  dogs  often  indi- 
cate the  arrival  or  departure  of  troops. 

In  abandoned  camps  indications  are  found  in  the  remains 
of  camp  fires.  They  show,  by  their  degrees  of  freshness,  whether 
much  or  little  time  elapsed  since  the  enemy  left  the  place, 
and  the  quantity  of  cinders  will  give  an  indication  of  the 
length  of  time  it  was  occupied,  as  well  as  furnishing  a  means 
of  estimating  the  force  approximately,  ten  men  being  allowed 
to  each  fire. 

A  knowledge  of  the  limits  of  vision  is  valuable.  On  a  clear 
day  a  man  with  good  eyesight  can  see: 

At  a  distance  of  9  to  12  miles,   church  spires  and  towers. 

At  a  distance  of  5  to  7  miles,  windmills. 

At  a  distance  of  2  to  2l/2  miles,  chimneys  of  light  color. 

At  a  distance  of  2000  yards,  trunks  of  large  trees. 

At  a  distance  of  1000  yards,  single  posts. 

At  500  yards,  the  panes  of  glass  in  a  window. 


RECOXX.-tlSS.-lXCE  501 

Troops  are  visible  at  2000  yards,  at  which  distance  a  mount- 
ed man  looks  like  a  mere  speck ;  at  1200  yards  infantry  can 
be  distinguished  from  cavalry;  at  1000  yards  line  of  men  looks 
like  a  broad  belt;  at  600  yards  the  files  of  a  squad  can  be  count- 
ed, and  at  400  yards  the  movements  of  arms  and  legs  can  be 
plainly  seen. 

FACTS     TO    OBTAIN 

Roads.  Their  direction,  their  nature  (macadamized,  cordu- 
roy, plank  direct,  etc.),  their  condition  of  repair,  their  grade, 
the  nature  of  crossroads,  and  the  points  where  they  leave  the 
main  roads;  their  borders  (woods,  hedges,  fences  or  ditches), 
the  places  at  which  they  pass  through  defiles,  cross  heights  or 
rivers,  and  where  they  intersect  railroads,  their  breadth 
(whether  suitable  for  column  of  fours  or  platoons,  etc.) 

Railroads.  Their  direction,  gauge,  the  number  of  tracks, 
stations  and  junctions,  their  grade,  the  length  and  height  of  the 
cuts,  embankments  and  tunnels. 

Bridges.  Their  position,  their  width  and  length,  their  con- 
struction (trestle,  girder,  etc.),  material  (wood,  brick,  stone  or 
iron),  the  roads  and  approaches  on  each  bank. 

Rivers  and  Other  Streams.  Their  direction,  width  and  depth, 
the  rapidity  of  the  current,  liability  to  sudden  rises  and  the 
highest  and  lowest  points  reached  by  the  water,  as  indicated 
by  drift  wood,  etc.,  fords,  the  nature  of  the  banks,  kinds,  posi- 
tion and  number  of  islands  at  suitable  points  of  passage,  heights 
in  the  vicinity  and  their  command  over  the  banks. 

Woods.  Their  situation,  extent  and  shape;  whether  clear  or 
containing  underbrush;  the  number  and  extent  of  "clearings" 
(open  spaces) ;  whether  cut  up  by  ravines  or  containing 
marshes,  etc.;  nature  of  roads  passing  through  them. 

Canals.  Their  direction,  width  and  depth ;  condition  of  tow- 
paths;  locks  and  means  of  protecting  or  destroying  them. 

Telegraphs.  Whether  they  follow  railroads  or  common 
roads ;  stations,  number  of  wires. 

Villages.  Their  situation  (on  a  height,  in  a  valley  or  on 
a  plain);  nature  of  the  surrounding  country;  construction  of 
the  houses,  nature  (straight  or  crooked)  and  width  of  streets; 
means  of  defense. 

Defiles.  Their*  direction;  whether  straight  or  crooked; 
whether  heights  on  either  side  are  accessible  or  inaccessible; 
nature  of  ground  at  each  extremity;  width  (frontage  of  column 
that  can  pass  through.) 

Ponds  and  Marshes.  Means  of  crossing;  defensive  use  that 
might  be  made  of  them  as  obstacles  against  enemy;  whether  the 
marshy  grounds  are  practicable  for  any  or  all  arms. 


502 


MILITARY  SIGNAL  CORPS  MANUAL 


Springs  and  Rivulets.  Nature  of  approaches;  whether  water 
is  drinkable  and  abundant. 

Valleys.  Extent  and  nature ;  towns,  villages,  hamlets, 
streams,  roads  and  paths  therein ;  obstacles  offered  by  or  in  the 
valley,  to  the  movement  of  troops. 

Heights.  Whether  slopes  are  easy  or  steep;  whether  good 
defensive  positions  are  offered;  whether  plateau  is  wide  or  nar- 
row; whether  passages  are  easy  or  difficult;  whether  the  ground 
is  broken  or  smooth,  wooded  or  clear. 


THE  PACK  STATION  OPEN  AND  WORKING,  AND  THE   GENERATOR 
MULE  WITH  MAST  SECTION 


MILITARY  MAP  READING 

When  you  pick  up  a  map,  the  first  question  is :  Where  is 
the  north?  This  can  usually  be  told  by  an  arrow  (see  fig.  1) 
which  will  be  found  in  one  of  the  corners  of  the  map,  and 
which  points  to  the  true  north— the  north  of  the  north  star. 

On  some  maps  no  arrow  is  to  be  found.  The  chances  are 
a  hundred  to  one  that  the  north  is  at  the  top  of  the  map, 
as  it  is  on  almost  all  printed  maps.  But  you  can  only  as- 
sure yourslf  of  that  fact  by  checking  the  map  with  the  ground 
it  represents.  For  instance,  if  you  ascertain  that  the  city  of 
Philadelphia  is  due  east  of  the  city  of  Columbus,  then  the 
Philadelphia-Columbus  line  on  the  map  is  a  due  east-and- 
west  line,  and  establishes  at  once  all  the  other  map  direc- 
tions. 

Let  it  be  understood  that  the  map  represents  the  ground 
as  nearly  as  it  can  be  represented  on  a  flat  piece  of  paper.  If 
you  are  standing  up  facing  the  north,  your  right  hand  will 
be  in  the  east,  your  left  in  the  west,  and  your  back  to  the 
south.  It  is  the  same  with  a  map;  if  you  look  across  it  in  the 
direction  of  the  arrow — that  is,  toward  its  north — your  right 
hand  will  be  toward  what  is  east  on  the  map;  your  left  hand 
to  the  west;  the  south  will  be  at  the  bottom  of  the  map. 

There  is  another  kind  of  an  arrow  that  sometimes  appears 
on  a  map.  It  is  like  the  one  in  figure  2,  and  points  not  to 
the  true  north,  but  to  the  magnetic  north,  which  is  the  north 
of  the  compass.  Though  the  compass  needle,  and  therefore 
the  arrow  that  represents  it  on  the  map,  does  not  point  ex- 
actly north,  the  deviation  is,  from  a  military  point  of  view, 
slight,  and  appreciable  error  will  rarely  result  through  the 
use  of  the  true  north  in  the  solution  of  any  military  problems. 

Should  you  be  curious  to  know  the  exact  deviation,  con- 
sult your  local  surveyor  or  any  civil  engineer. 

Both  arrows  may  appear  on  your  map.  In  that  case  dis- 
regard the  magnetic  arrow  unless  you  are  using  the  map  in 
connection  with  a  compass. 

503 


504  MILITARY  SIGNAL  CORPS  MANUAL 

If  a  map  is  being  used  on  the  ground,  the  first  thing  to 
be  done  is  to  put  the  lines  of  the  map  parallel  to  the  real  out- 
lines of  the  ground  forms,  and  roads,  fences,  railroads,  etc., 
that  the  map  shows ;  for  the  making  of  a  map  is  no  more  than 
the  drawing  on  paper  of  lines  parallel  to  and  proportional  in 
length  to  real  directions  and  distances  on  the  ground. 

For  instance,  the  road  between  two  places  runs  due  north 
and  south.  Then  on  the  map  a  line  representing  the  road  will 
be  parallel  to  the  "arrow  showing  the  north  and  will  be  pro- 
portional in  length  to  the  real  road.  In  this  way  a  map  is 
a  picture,  or,  better,  a  bare  outline  sketch ;  and,  as  we  can 
make  out  a  picture,  though  it  be  upside  down,  or  crooked  on 
the  wall,  so  we  can  use  a  map  that  is  upside  down  or  not 
parallel  to  the  real  ground  forms.  But  it  is  easier  to  make  out 
both  the  picture  and  the  map  if  their  lines  are  parallel  to  what 
they  represent.  So  in  using  a  map  on  the  ground  the  lines 
are  always  placed  parallel  to  the  actual  features  they  show. 
This  is  easy  if  the  map  has  an  arrow. 

If  the  map  has  no  arrow,  you  must  locate  some  objects 
or  features  on  the  ground,  and  on  the  map,  their  representa- 
tions. Draw  on  the  map  a  line  connecting  any  two  of  the 
features ;  place  this  line  parallel  to  an  imaginary  line  through 
the  two  actual  features  located,  and  your  map  will  be  cor- 
rectly placed.  Look  to  it  that  you  do  not  reverse  on  the  map 
the  positions  of  the  two  objects  or  features,  or  your  map  will 
be  exactly  upside  down. 

When  the  map  has  been  turned  into  the  proper  position — 
that  is  to  say,  "oriented" — the  next  thing  is  to  locate  on  the 
map  your  position.  If  you  are  in  the  village  of  Easton  and 
there  is  a  place  on  the  map  labeled  Easton,  the  answer  is  ap- 
parent. But  if  you  are  out  in  the  country,  at  an  unlabeled 
point  that  looks  like  any  one  of  a  dozen  other  similar  points, 
the  task  is  more  complicated.  In  this  latter  case  you  must  lo- 
cate and  identify,  both  on  the  map  and  on  the  ground,  other  points 
— hills,  villages,  peculiar  bends  in  rivers,  forests— any  ground 
features  that  have  some  easily  recognizable  peculiarity  and  that 
you  can  see  from  your  position. 

Suppose,  for  instance,  you  were  near  Leavenworth  and  want- 
ed to  locate  your  exact  position,  of  which  you  are  uncertain.  You 
refer  to  the  map,  and,  looking  about,  you  see  southwest  from  where 
you  stand  the  United  States  Penitentiary;  also,  halfway  between 
the  south  and  the  southeast — south-southeast  a  sailor  would  say — the 
reservoir  (rectangle  west  of  "O"  in  "Missouri").  Having  oriented 
your  map,  draw  on  it  a  line  from  the  map  position  of  the  reservoir 
toward  its  actual  position  on  the  ground.  Similarly  draw  a  line 
from  the  map  position  of  penitentiary  toward  its  actual  position. 


505 


506  MILITARY  SIGXAL  CORPS  MANUAL 

Prolong  the  two  lines  until  they  intersect;  the  intersection  of  the 
lines  will  mark  the  place  where  you  stand — south  Merritt  Hill. 

This  method  consists  merely  in  drawing  on  the  map  lines  that 
represent  the  lines  of  sight  to  known  and  visible  places.  The  lines 
pass  through  the  map  position  of  the  places  you  see  and  are 
parallel  to  the  actual  lines  of  sight ;  therefore  they  are  the  map 
representations  of  the  lines  of  sight,  and  their  intersection  is  the 
map  position  of  the  eye  of  the  observer. 

After  this  orientation  and  location  of  position,  one  can  deduce 
from  the  map  everything  there  is  to  know  in  regard  to  directions. 
In  this  respect,  study  of  the  ground  itself  will  show  no  more  than 
will  study  of  the  map.  ^ 

After  "What  direction?"  comes  "How  far?"*  To  answer  this, 
one  must  understand  that  the  map  distance  between  any  two  points 
shown  bears  a  fixed  and  definite  relation  or  proportion  to  the  real 
distance  between  the  two  points. 

For  instance :  We  measure  on  a  map  and  find  the  distance  be- 
tween two  points  to  be  1  inch.  Then  we  measure  the  real  distance 
on  the  ground  and  find  it  to  be  10,000  inches ;  hence  the  relation 
between  the  map  distance  and  the  real  distance  is  1  to  10,000  or 
1-10000.  Now,  if  the  map  is  properly  drawn  the  same  relation  will 
hold  good  for  all  distances,  and  we  can  obtain  any  ground  dis- 
tance by  multiplying  by  10,000  the  corresponding  map  distance. 

This  relation  need  not  be  1-10000,  but  may  be  anything  from 
1-100  that  an  architect  might  use  in  making  a  map  or  plan  of  a 
house  up  to  one  dver  a  billion  and  a  half,  which  is  about  the  pro- 
portion between  map  and  real  distances  in  a  pocket-atlas  repre- 
sentation of  the  whole  world  on  a  6-inch  page.  Map  makers  call 
this  relation  the  "scale"  of  the  map  and  put  it  down  in  a  corner 
in  one  of  three  ways. 

For  the  sake  of  an  illustration,  say  the  relation  between  map 
and  ground  distances  is  1  to  100;  that  is,  1  inch  on  the  map  is 
equal  to  100  on  the  ground.  The  scale  may  be  written: 

First.  1  inch  equals  100. 

Second.  1-100. 

Third.  As  shown  by  figure  3. 

These  expressions  mean  one  and  the  same  thing.  A  variation 
of  the  first  method  on  a  map  of  different  scale  might  be :  1  inch 
equals  1  mile.  Since  a  mile  contains  63,360  inches,  then  the  real 
distance  between  any  two  points  shown  on  the  map  is  63,360  times 
the  map  distance. 

To  find  the  ground  distance  by  the  third  kind  of  scale,  copy  it 
on  the  edge  of  a  slip  of  paper,  apply  the  slip  directly  to  the  map, 
and  read  off  the  distance ;  and  so  we  answer  the  question,  "How 
far?" 


507 


Soil  and  Cultivation. 


Woods.      Grass  ot  meadow.   Cultivated. 


Enclosures, 
Wire  Fence 


Communications. 


Public  RovL. 

______ ____x 

Wagon  trail. 


T  TT  T 

Telegraph. 


R.R.  tingle  track. 


Stone  fence. 


Hedge. 


Foot  or  bridle  trail. 


FUI 


20' 

Cut 


Bridges. 


R.R.  double  track. 


Tunnel. 


CONVENTIONAL  SIGNS  FOR   MILITARY  MAPS 


MILITARY  SIGXAL  CORPS  MAXUAL 


Telegraph,  Line-  _ 


Railroads 


Single'  Sraak  * 
Double,  &a6k 


Two  Railroads       r± 
Urban,  or  .  —  .  _  . 
Suburban,  ..,_ 


Wagon 


1#  Class  Metaled  .... 


2*2  Class..  Cf)iattry  Radii; 
(good) 


..Country  Rocul : 
(poor) 


"but  exit  out 
Steep  Incline.- 


Rood  Crossings 


Grade'  ______________ 


*2oir  GraJ3& 


CONVENTIONAL   SIGNS   FOR  MILITARY  MAPS 


MAP  READING 


509 


After  direction  and  distance  comes  the  interpretation  of  the 
signs,  symbols,  and  abbreviations  on  the  map.  Those  authorized 
are  given,  but  there  are  a  good  many  other  conventional  signs  in 
common  use.  A  key  to  them  is  published  by  the  War  Department 
and  is  called  "Conventional  Signs,  United  States  Army."  From 
these  you  read  at  once  the  natural  and  artificial  features  of  the 
country  shown  on  your  map.  It  should  be  borne  in  mind  that 


zoo  INCHES 


Fig.  10. 


F.g.ll. 


ELEMENTARY  GUIDE   FOR  THE  STUDY  OF  MAP  CONTOURS 

these  conventional  signs  are  not  necessarily  drawn  to  scale,  as  are 
the  distances.  They  show  the  position  and  outline  of  the  features, 
rather  than  the  size.  This,  for  the  reason  that  many  of  the 
features  shown,  if  drawn  to  scale,  would  be  so  small  that  one 
could  not  make  them  out  except  with  a  magnifying  glass.  If  the 
exact  dimensions  are  of  any  importance  they  will  be  written  in 
figures  on  the  map.  For  instance,  bridges. 

In    addition    to    the    conventional    signs,    we    have    contours   to 
show  the  elevations,  depressions,   slope,  and  shape  of  the  ground. 


510  MILITARY  SIGNAL  CORPS  MANUAL 

Abroad,  hachures  are  much  used,  but  they  serve  only  to  in- 
dicate elevation,  and  as  compared  to  contours  are  of  little  value. 
Contours  resemble  the  lines  shown  in  figure  4. 

Hachures  are  shown  in  figure  5,  and  may  be  found  on  any 
European  map.  They  simply  show  slopes  and,  when  carefully 
drawn,  show  steeper  slopes  by  heavier  shading  and  gentler  slopes 
by  the  fainter  hachures.  The  crest  of  the  mountain  is  within  the 
hachures.  (See  fig.  5.) 

CONTOURS 

A  certain  student  when  asked  by  his  instructor  to  define  "space" 
said :  "I  have  it,  sir,  in  my  head,  but  can  not  put  it  into  words." 
The  instructor  replied :  "I  suppose  that  under  those  circumstances, 
Mr.  ,  the  definition  really  would  not  help  much." 

And  so  it  is  with  contours ;  the  definition  does  not  help  much 
if  you  know  a  contour  when  you  meet  it  on  a  map.  For  examples 
of  contours  turn  to  the  map  and,  starting  at  the  United  States 
Penitentiary,  note  the  smooth,  flowing,  irregular  curved  lines  marked 
880,  860,  840,  860,  etc. 

The  only  other  lines  on  the  map  that  at  all  resemble  contours 
are  stream  lines,  like  "Corral  Creek,"  but  the  stream  lines  are 
readily  distinguished  from  contours  by  the  fact  that  they  cross 
the  contours  squarely,  while  the  contours  run  approximately  parallel 
with  each  other.  Note  the  stream  line  just  to  the  west  of  South 
Merritt  Hill. 

The  contours  represent  lines  on  the  ground  that  are  horizontal 
and  whose  meanderings  follow  the  surface,  just  as  the  edge  of  a 
flood  would  follow  the  irregularities  of  the  hills  about  it.  Those 
lines  that  contours  stand  for  are  just  as  level  as  the  water's  edge 
of  a  lake,  but  horizontally  they  wander  back  and  forth  to  just  as 
great  a  degree. 

The  line  marked  880  at  the  penitentiary  passes  through,  on  that 
particular  piece  of  ground,  every  point  that  is  880  feet  above 
sea  level.  Should"  the  Missouri  River  rise  in  flood  to  880  feet,  the 
penitentiary  would  be  on  an  island,  the  edge  of  which  is  marked 
by  the  880  contour. 

Contours  show  several  things ;  among  them  the  height  of  the 
ground  they  cross.  Usually  the  contour  has  labeled  on  it  in  figures 
the  height  above  some  starting  point,  called  the  datum  plane 
— generally  sea  level.  If,  with  a  surveying  instrument,  you  put 
in  on  a  piece  of  ground  a  lot  of  stakes,  each  one  of  which  is 
exactly  the  same  height  above  sea  level — that  is.  run  a  line  of 
levels — then  make  a  map  showing  the  location  of  the  stakes,  a  line 
drawn  on  the  map  through  all  the  stake  positions  is  a  contour 
and  shows  the  position  of  all  points  of  that  particular  height. 


MAP  READING  511 

On  any  given  map  all  contours  are  equally  spaced  in  a  vertical 
direction,  and  the  map  shows  the  location  of  a  great  number  of 
points  at  certain  fixed  levels.  If  you  know  the  vertical  interval 
between  any  two  adjacent  contours,  you  know  the  vertical  interval 
for  all  the  contours  on  that  map,  for  these  intervals  on  a  given 
map  are  all  the  same. 

With  reference  to  a  point  through  which  no  contour  passes, 
we  can  only  say  the  point  in  question  is  not  higher  than  the  next 
contour  up  the  hill,  nor  lower  than  the  next  one  down  the  hill. 
For  the  purposes  of  any  problem,  it  is  usual  to  assume  that  the 
ground  slopes  evenly  between  the  two  adjacent  contours,  and  that 
the  vertical  height  of  the  point  above  the  lower  contour  is  pro- 
portional to  its  horizontal  distance  from  the  contour,  as  com- 
pared to  the  whole  distance  between  the  two  contours.  '  For  in- 
tance,  on  the  map,  find  the  height  of  point  A.  The  horizontal 
measurements  are  as  shown  on  the  map.  The  vertical  distance 
between  the  contours  is  20  feet,  A  is  about  one-quarter  of  the 
distance  between  the  800  and  the  820  contours,  and  we  assume  its 
height  to  be  one-quarter  of  20  feet  (5  feet)  higher  than  800  feet. 
So  the  height  of  A  is  805  feet. 

The  vertical  interval  is  usually  indicated  in  the  corner  of  the 
map  by  the  letters  "V.  I."  For  instance,  V.  I .=20  feet. 

On  maps  of  very  small  pieces  of  ground,  the  V.  I.  is  usually 
small — perhaps  as  small  as  1  foot ;  on  maps  of  large  areas  on 
a  small  scale  it  may  be  very  great — even  1,000  feet. 

Contours  also  show  slopes.  It  has  already  been  explained 
that  from  any  contour  to  the  next  one  above  it  the  ground  rises 
a  fixed  number  of  feet,  according  to  the  vertical  interval  of  that 
map.  From  the  scale  of  distances  on  the  map  the  horizontal 
distance  between  any  two  contours  can  be  found.  For  example: 


370 


On  the  map,  the  horizontal  distance  between  D  and  E  is  90  yards, 
or  270  feet.  The  vertical  distance  is  20  feet  the  V.  I.  of  the  map. 
The  slope  then  is  20/270=1 713.5=7^  %=4%°  jn  all  of  which  differ- 
ent ways  the  slope  can  be  expressed. 

On  a  good  many  contoured  maps  a  figure  like  this  will  be  found 
in  one  of  the  corners : 


j_ 2°      i  3°   i4°i  5< 


512  MILITARY  SIGXAL  CORI'S  MAXTAL 

On  that  particular  map  contours  separated  by  the  distance 

1° 

i  *  I 

on  the  vertical  scale  show  a  slope  of  1°.  A  slope  of  1°  is  a  rise 
of  1  foot  in  57.  To  use  this  scale  of  slopes  copy  it  on  the  edge 
of  a  piece  of  paper  just  as  you  did  the  scale  of  distances  and  ap- 
ply it  directly  to  the  map. 

You  will  notice  that  where  the  contours  lie  closest  the  slope  is 
steepest ;  where  they  are  farthest  apart  the  ground  is  most  nearly 
flat. 

It  has  already  been  set  forth  how  contours  show  height  and 
slope ;  in  addition  to  this  they  show  the  shape  of  the  ground,  or 
ground  forms.  Each  single  contour  shows  the  shape  at  its 
particular  level  of  the  hill  or  valley  it  outlines;  for  instance  the 
880  contour  about  the  penitentiary  shows  that  the  hill  at  that 
level  has  a  shape  somewhat  like  a  horse's  head.  Similarly  every 
contour  on  the  map  gives  us  the  form  of  the  ground  at  its  particu- 
lar level,,  and  knowing  these  ground  forms  for  many  levels  we 
can  form  a  fair  conception  of  what  the  whole  surface  is  like. 

A  round  contour  like  the  letter  O  outlines  a  round  ground 
feature ;  a  long  narrow  one  indicates  a  long  narrow  ground  feature. 

Different  hills  and  depressions  have  different  shapes.  A  good 
many  of  them  have  one  shape  at  one  level  and  another  shape  at 
another  level,  all  of  which  information  will  be  given  you  by  the 
contours  on  the  map. 

One  of  the  ways  to  see  how  contours  show  the  shape  of  the 
ground  is  to  pour  half  a  bucket  of  water  into  a  small  depression 
in  the  ground.  The  water's  edge  will  be  exactly  level,  and  if  the 
depression  is  approximately  round,  the  water's  edge  will  also  be 
approximately  round.  The  outline  will  look  something  like  fig- 
ure 6. 

Draw  roughly  on  a  piece  of  paper  a  figure  of  the  same  shape 
and  you  will  have  a  contour  showing  the  shape  of  the  bit  of 
ground  where  you  poured  your  water. 

Next,  with  your  heel  gouge  out  on  one  edge  of  your  little 
pond  a  small  round  bay.  The  water  will  rush  in  and  the  water- 
mark on  the  soil  will  now  be  shaped  something  like  figure  7. 

Alter  your  drawing  accordingly,  and  the  new  contour  will  show 
the  new  ground  shape. 

Again  do  violence  to  the  face  of  nature  by  digging  with  a  stick 
a  narrow  inlet  opening  out  of  your  miniature  ocean,  and  the  water- 
mark will  now  look  something  like  figure  8. 


MAP  READING  513 

Alter  your  drawing  once  more  and  your  contour  shows  again 
the  new  ground  form.  Drop  into  your  main  pond  a  round  clod 
and  you  will  have  a  new  watermark,  like  figure  9,  to  add  to  your 
drawing.  This  new  contour,  of  the  same  level  with  the  one  snow- 
ing the  limit  of  the  depression,  shows  on  the  drawing  the  round 
island. 

Drop  in  a  second  clod,  this  time  long  and  narrow;  the  water- 
mark will  be  like  figure  10,  and  the  drawing  of  it,  properly  placed, 
will  show  another  island  of  another  shape.  Your  drawing  now 
will  look  like  figure  11. 

It  shows  a  depression  approximately  round,  off  which  open  a 
round  bay  and  a  long  narrow  bay.  There  is  also  a  round  eleva- 
tion and  a  long  narrow  one;  a  long,  narrow  ridge,  jutting  out  be- 
tween the  two  bays,  and  a  short,  broad  one  across  the  neck  of 
the  round  bay. 

Now  flood  your  lake  deeply  enough  to  cover  up  the  features  you 
have  introduced.  The  new  water  line,  about  as  shown  by  the 
dotted  line  in  figure  11,  shows  the  oblong  shape  of  the  depression 
at  a  higher  level ;  the  solid  lines  show  the  shape  farther  down ; 
the  horizontal  distance  between  the  two  contours  at  different 
points  shows  where  the  bank  is  steep  and  where  the  slope  is  gentler. 

Put  together  the  information  that  each  of  these  contours  gives 
you,  and  you  will  see  how  contours  show  the  shape  of  the  ground. 
On  the  little  map  you  have  drawn  you  have  introduced  all  the  va- 
rieties of  ground  forms  there  are;  therefore  all  the  contour  forms. 

The  contours  on  an  ordinary  map  seem  much  more  compli- 
cated, but  this  is  due  only  to  the  number  of  them,  their  length, 
and  many  turns  before  they  finally  close  on  themselves.  Or  they 
may  close  off  the  paper.  But  trace  each  one  out,  and  it  will  resolve 
itself  into  one  of  the  forms  shown  in  figure  11. 

Just  as  the  high-tide  round  the  continents  of  North  and  South 
America  runs  a  long  and  tortuous  course,  but  finally  closes  back 
on  itself,  so  will  every  contour  do  likewise.  And  just  as  truly 
as  every  bend  in  that  high-tide  mark  turns  out  around  a  promon- 
tory, or  in  around  a  bay,  so  will  every  bend  in  a  contour  stand 
for  a  hill  or  a  valley  pointing  to  the  lowlands  if  it  be  a  hill,  and 
to  the  height  if  it  mark  a  valley. 

If  the  map  embrace  a  whole  continent  or  an  island,  all  the  con- 
tours will  be  of  closed  form,  as  in  figure  11,  but  if  it  embrace 
only  a  part  of  the  continent  or  island,  some  of  the  contours  will 
be  chopped  off  at  the  edge  of  the  map,  and  we  have  the  open 
form  of  contours,  as  we  would  have  if  figure  11  were  cut  into 
two  parts. 

The  closed  form  may  indicate  a  hill  or  a  basin;  the  open  form, 
a  ridge  or  a  valley;  sometimes  a  casual  glance  does  not  indicate 
which. 


514 


MILITARY  SIGNAL  CORPS  MAX  UAL 


Take  up,  first,  the  contour  of  the  open  type.  If  the  map  shows 
a  stream  running  down  the  inside  of  the  contour,  there  is  no  dif- 
ficulty in  saying  at  once  that  the  ground  feature  is  a  valley ;  for 
instance,  V,  V,  V,  and  the  valley  of  Corral  Creek  on  the  map. 
But  if  there  is  no  stream  line,  does  the  contour  bend  show  a  valley 
or  a  ridge? 

First  of  all,  there  is  a  radical  difference  between  the  bend  of 
a  contour  round  the  head  of  a  valley  and  its  bend  round  the  nose 
of  a  ridge. 

Compare  on  the  map  the  valleys  V  and  the  ridges  R.  The  bend 
of  the  contour  round  the  head  of  the  valley  is  much  sharper  than 
the  bend  of  the  contour  round  the  nose  of  the  ridge.  This  is  a 


OUTLINE   LANDSCAPE    PRACTICE   SKETCHES   USEFUL    FOR   GRASP- 
ING THE   ESSENTIALS  OF  TERRAIN 

general  truth,  not  only  in  regard  to  maps,  but  also  in  regard  to 
ground  forms.  Study  any  piece  of  open  ground  and  note  how  much 
wider  are  the  ridges  than  the  valleys.  Where  you  find  a  "hog 
back"  or  "devil's  backbone,"  you  have  an  exception  to  the  rule, 
but  the  exceptions  are  not  frequent  enough  to  worry  over. 

To  tell  whether  a  given  point  is  on  a  ridge  or  in  a  valley, 
start  from  the  nearest  stream  shown  on  the  map  and  work  across 
the  map  to  the  undetermined  point,  keeping  in  mind  that  in  a  real 
trip  across  the  country  you  start  from  the  stream,  go  up  the  hill  to 
the  top  of  a  ridge,  down  the  other  side  of  the  hill  to  a  water- 
course, then  up  a  hill  to  the  top  of  a  ridge,  down  again,  up  again, 
and  so  on.  That  is  all  traveling  is — valley,  hill,  valley,  hill,  valley 
—though  you  wander  till  the  crack  o'  doom.  And  so  your  map 


MAP  READING  515 

travels  must  go — valley,  hill,  valley,  hill — till  you  run  off  the 
map  or  come  back  to  the  starting  point. 

On  the  map,  follow  the  R-V  line,  V  indicating  valley  and  R 
ridge  or  hill.  Note  first  the  difference  in  sharpness  in  the  con- 
tour bends ;  also  how  the  valley  contours  point  to  the  highland 
and  the  ridge  contours  to  the  lowland. 

The  streams  flow  down  the  valleys,  and  the  sharp  angle  of  the 
contour  points  always  UP  stream.  Note  also  how  the  junction 
of  a  stream  and  its  tributary  usually  makes  an  angle  that  points 
dozen  stream. 

"Which  way  does  this  stream  run?" 

Water  flows  down  hill.  If  you  are  in  the  bed  of  a  stream, 
contours  representing  higher  ground  must  be  to  your  right  and  to 
your  left.  Get  the  elevations  of  these  contours.  Generally  the 
nearest  contour  to  the  bank  of  the  stream  will  cross  the  stream 
and  there  will  be  an  angle  or  sharp  turn  in  the  contour  at  this 
crossing.  If  the  point  of  the  angle  or  sharp  turn  is  toward  you, 
you  are  going  downstream ;  if  away  from  you,  you  are  going  up- 
stream. 

If  the  contours  are  numbered,  you  have  only  to  look  at  the 
numbers  to  say  where  the  low  and  where  the  high  places  are ;  but 
to  read  a  map  with  any  speed  one  must  be  quite  independent  of 
these  numbers.  In  ordinary  map  reading  look,  first  of  all,  for 
the  stream  lines.  The  streams  are  the  skeleton  upon  which  the 
whole  map  is  hung.  Then  pick  out  the  hilltops  and  ridges  and 
you  have  a  body  to  clothe  with  all  the  details  that  will  be  re- 
vealed by  a  close  and  careful  study  of  what  the  map  maker  has 
recorded. 

As  to  closed  contours,  they  may  outline  a  depression  or  a  hill. 
On  the  map,  "881"  or  "885"  might  be  hills  or  ponds,  as  far  as 
their  shape  is  concerned.  But,  clearly,  they  are  hills,  for  on  either 
side  are  small  streams  running  away  from  them.  If  they  were 
ponds  the  stream  lines  would  run  toward  the  closed  contours. 
The  test  of  "hill,  valley,  hill,"  will  always  solve  the  problem  when 
there  are  not  enough  stream  lines  shown  to  make  evident  at  once 
whether  a  closed  contour  marks  a  pond  or  a  hill.  Look  in  the 
beginning  for  the  stream  lines  and  valleys,  and,  by  contrast,  if 
for  no  other  reason,  the  hills  and  ridges  at  once  loom  up. 

To  illustrate  in  armories  or  drill  halls  the  subject  of  contours 
to  aid  those  who  have  difficulty  in  reading  contoured  maps  the 
following  is  suggested : 

1.  Secure  modeling  clay  and  build  a  mound. 

2.  Use  wire  and  slice  this  mound  horizontally  at  equal  vertical 
intervals  into  zones ;  then  insert  vertical  dowels  through  the  mound 
of  clay. 


516  MILITARY  SIGNAL  CORPS  MANUAL 

3.  Remove  the  top  zone,  place  on  paper,  and  draw  outline  of 
the  bottom  edge.     Trim  your  paper  roughly  to  the  outline  drawn 
Indicate  where  the  holes  made  by  the  dowels  pierce  the  paper. 

4.  Do  the  foregoing  with  each  zone  of  your  mound. 

5.  Place  these  papers  in  proper  order  on  dowels  similarly  placed 
to   those  in  original  mound  at,   say,   1    inch  vertical   intervals.     A 
skeleton  mound  results. 

6.  Replace  the  zones  of  the  clay  mound  and  form  the  original 
•  clay  mound  along  the  side  of  skeleton  mound. 

7.  Now  force  all  the  paper  sheets  down  the  dowels   onto  the 
bottom  sheet,  and  we  have  a  map  of  clay  mound  with  contours. 

Note. — One-inch  or  2-inch  planks  can  be  made  into  any  desired 
form  by  the  use  of  dowels  and  similar  procedure  followed. 

It  is  frequently  asked,  "What  should  I  see  when  I  read  a 
map?"  and  the  answer  is  given,  "The  ground  as  it  is."  This  is 
not  true  any  more  than  it  is  true  that  the  words,  "The  valley 


Indicate  character  and  span  by  abbreviations. 


Example: 

It        *>*«) 

io 

Meaning  wooden  kingpost  bridfe,40feet  long.  20 feet  wkte. 
and  10  feet  above  the  water. 


Streams 


'.Indicate  character,  by  abbreviaftwa 


Meaninfcastream  15  feet  wide,8feet  deep.  and  opt  fbrdabte. 
House  •  Church*  School  house  -SH. 

Woods    ^Wpods\  Oroharxfeg^O  Cultivated  Land  (Cult  ! 

If  boundary  lines  are  fences  they  are  indicated  as  such 
Brush,  crops  or  grass,  important  as  coveror  forage  Igggff^l 
Cemetery      1  *+  *»  %j  Treea.«o!ate3      •»*. 

Cutandfill-  \  Cut    ';       cut  IQfeet  deep 

.   ;  ""     ;  •     filHOfeethi4h 


MAP  READING 


517 


of  the  Meuse,"  bring  to  your  mind  vine-clad  hills,  a  noble  river, 
and  green  fields  where  cattle  graze.  Nor  can  any  picture  ever 
put  into  your  thought  what  the  Grand  Canyon  really  is.  What 
printed  word  or  painted  picture  can  not  do,  a  map  will  not  A 
map  says  to  you,  "Here  stands  a  hill,"  "Here  is  a  valley,"  "This 
stream  runs  so,"  and  gives  you  a  good  many  facts  in  regard  to 
them.  But  you  do  not  have  to  "see"  anything,  any  more  than 
you  have  to  visualize  Liege  in  order  to  learn  the  facts  of  its 
geography.  A  map  sets  forth  cold  facts  in  an  alphabet  all  its 
own,  but  an  easy  alphabet,  and  one  that  tells  with  a  few  curving 
lines  more  than  many  thousand  words  could  tell. 


FIELD    MAPS    AND    SKETCHES 

The  following  abbreviations,  and  the  signs  on  preceding  page,  are 
authorized  for  use  on  field  maps  and  sketches.  For  more  elaborate 
map  work  the  authorized  conventional  signs  as  given  in  the  manual 
of  "Conventional  Signs,  United  States  Army  Maps,"  are  used. 

Abbreviations  other  than  those  given   should  not  be  used. 

ABBREVIATIONS 


Shop 


A. 

Arroyo 

abut. 

Abutment 

Ar. 

Arch 

b. 

Brick 

B.  S. 

Blacksmith 

bot. 

Bottom 

Br. 

Branch 

br. 

Bridge 

C. 

Cape 

cem. 

Cemetery 

con. 

Concrete 

cov. 

Covered 

Cr. 

Creek 

d. 

Deep 

cul. 

Culvert 

D.  S. 

Drug  Store 

E. 

East 

Est. 

Estuary 

f. 

Fordable 

Ft. 

Fort 

G.  S. 

General  Store 

Pt. 

Point 

gir. 
G.  M. 

Girder 
Gristmill 

r- 

Queen  -post 
River 

I. 

Iron 

R.  H. 

Roundhouse 

I. 

Island 

R.  R. 

Railroad 

L%. 

Junction 
King-post 

S. 
s. 

South 
Steel 

L. 

Lake 

S.  H. 

Schoolhouse 

Lat. 

Latitude 

S.  M. 

Sawmill 

Ldg. 

Landing 

Sta. 

Station 

L.S.  S. 

Life-Saving   Sta. 

St. 

Stone 

L.  H. 

Lighthouse 

str. 

Stream 

Long. 

Longitude 

T.  G. 

Tollgate 

Mt. 

Mountain 

Tres. 

Trestle 

Mts. 

Mountains 

tr. 

Truss 

N. 

North 

W.T. 

Water  Tank 

n.  f. 

Not  fordable 

W.W. 

Water  Works 

P. 

Pier 

W. 

West 

pk. 

Plank     • 

w. 

Wood 

P.O. 

Post  Office 

wd. 

Wide 

MILITARY  SKETCHING  FOR  BEGINNERS 

Pencils  are  to  be  sharpened  and  an  eraser  handy;  only  ex- 
perts can  sketch  with  dull  pencils.  Use  hard  pencils  when 
learning  to  sketch. 

Leave  out  of  your  sketch  the  minor  details  that  are  too 
small  to  be  shown  on  the  scale  at  which  you  are  sketching. 
If  you  are  making  a  sketch  on  a  scale  of  3  inches  =  1  mile,  do 
not  try  to  show  each  house  in  a  row;  simply  indicate  the  row 
of  houses  by  putting  down  several  distinct  conventional  signs 


518 


MILITARY  SIGNAL  CORPS  MANUAL 


for  houses  in  a  row.  And  don't  try  to  show  every  little  "cut" 
through  which  the  road  may  run.  Only  use  about  one  sign  to 
the  inch  for  telegraph  or  telephone  lines,  for  wire  fences,  and 
similar  details. 


THE  SKETCHING  CASE  USED  IN  THE  ARMY 

When  practising,  plot  only  the  route  over  which  you  walk, 
indicating  it  by  a  single  line.    When  you  can  do  this  with  facil- 


PREPARING  AN  ELEMENTARY  MILITARY  MAP  OF  A  NEW 
CAMP  LOCATION 


MAP   READING 


519 


Military  Signs. 
Infantry 

In  column    oo-O-OO-O 

Cavalry 
In  column    E  E  E  E  E  C* 


Artillery          +  *  t   *  t 
Sentrv  Vedettt 


Palisades 


Wire 
entanglement 


AAAAAA 


Trenches 


Mortar 
battery 


Abatti. 
Chevaux  de 


Miscellaneous. 

Regimental  Headquarters^^^ ._ 

Brigade-  i_, . 


Signal  Carps; 


Quarter-master .. 
Commissary  — — 


520  MILITARY  SIGNAL  CORPS  MANUAL 

ity,  go  back  over  one  of  these  plotted  routes  and  fill  in  the 
woods,  houses,  streams  and  the  other  large  features. 

As  a  beginner,  sketch  the  same  ground  several  times  over — 
at  least  three  or  four  times.  Compare  the  result  for  practice 
in  accuracy. 

Always  try  to  compare  your  finished  sketch  with  an  accurate 
map  of  the  ground,  if  one  is  obtainable.  Try  to  practice  on 
ground  of  which  you  can  obtain  a  map. 

Make  each  course — that  is,  the  distance  you  go  between 
points  where  the  direction  of  your  route  changes — as  long  as 
possible. 

Do  not  try  to  contour  until  you  are  expert  at  making  a 
sketch  showing  all  the  flat  details  (roads,  streams,  woods, 
houses,  etc.)- 

Never  try  to  "sketch  in"  the  contours  until  you  have  plotted 
the  stream  lines  or  the  direction  of  the  valleys  and  ravines. 
The  contours  are  sketched  around  or  fitted  to  the  drainage 
system;  not  the  drainage  system  to  the  contours. 

Always  "size  up"  ground  before  you  sketch  it.  Take  a  gen- 
eral view,  noticing  the  drainage  system  (the  direction  in  which 
the  streams  flow  or  ravines  run),  the  prominent  hills  and 
ridges,  the  direction  the  roads  run,  and  similar  details. 


SIGNAL    TROOPS    IN    FIELD    SERVICE 

POSITION 

The  position  of  signal  troops  is  governed  by  the  tactical  re- 
quirements of  the  situation.  Detachments  of  signal  troops 
must  necessarily,  whether  on  the  march,  in  camp,  or  in  com- 
bat, be  near  the  commanding  officer  of  the  troops  with  whom 
communication  must  be  maintained. 

To  this  end  commanding  officers  of  signal  troops  will  make 
such  distribution  of  their  command  as  will  enable  signal 
troops  to  best  secure  this  result  without  interfering  with  the 
function  of  other  troops. 

The  position  of  the  signal  officer  is  usually  with  the  com- 
manding general  or  with  the  commanding  officer  of  the  unit 
for  which  he  is  furnishing  lines.  From  this  point  he  can  get 
a  grasp  of  the  situation  and  be  able  to  direct  the  operations 
of  his  platoons  and  sections  to  the  best  advantage.  All  con- 
templated changes  in  the  location  of  wire  carts  and  stations 
are  reported  to  him. 

MARCHES 

With  new  or  untrained  troops  the  process  of  hardening 
must  be  gradual.  Marches  should  begin  with  a  distance  of  2 
or  3  miles  and  increase  as  the  men  become  accustomed  to 
bearing  arms  and  equipment  without  fatigue.  . 

A  long  march  should  not  be  made  with  untrained  troops. 

Special  attention  should  be  paid  to  the  fitting  of  shoes  and 
the  care  of  feet.  Shoes  should  not  be  too  wide  or  too  short. 
Sores  and  blisters  on  the  feet  should  be  promptly  dressed 
during  halts.  At  the  end  of  the  march,  feet  should  be  bathed 
and  dressed;  the  socks,  and,  if  practicable,  the  shoes  should 
be  changed. 

Drinking  water  on  the  march  should  be  avoided;  its  use 
should  in  general  be  confined  to  gargling  the  mouth  and 
throat  or  to  an  occasional  small  drink  at  most. 

521 


522  MILITARY  SIGNAL  CORPS  MANUAL 

Marches  should  not  begin  before  an  hour  after  daylight. 

A  halt  of  15  minutes  should  be  made  after  the  first  half  or 
three-quarters  of  an  hour  of  marching,  thereafter  a  halt  of  10 
minutes  is  made  in  each  hour.  The  number  and  length  of  halts 
may  be  varied,  according  to  the  weather,  the  condition  of  the 
roads,  and  the  equipment  carried. 

The  position  of  companies  in  the  battalion  is  ordinarily 
changed  so  that  each  company  in  turn  leads,  for  the  reason 
that  marching  at  the  rear  of  the  column  is  more  disagree- 
able and  fatiguing  than  marching  at  the  front. 

An  officer  of  each  company  marches  in  its  rear  to  prevent 
undue  elongation  and  straggling. 

Chiefs  of  platoons  and  of  sections,  without  waiting  for  ex- 
press instruction,  give  such  orders  as  may  be  necessary  for 
helping  a  wagon  out  of  difficulties.  All  men  of  the  section 
may  be  used  for  this  purpose  if  necessary. 

When  an  accident  happens  to  a  wagon  it  is  pulled  out  of 
the  column,  if  possible,  so  as  not  to  interrupt  the  march ; 
otherwise,  sections  in  rear  pass  it  by  on  the  most  convenient 
flank,  so  as  not  to  delay  the  march.  Its  place  in  the  column  is 
resumed  when  the  damage  is  repaired,  as  soon  as  it  is  possi- 
ble to  pass  the  intervening  sections.  If  a  section  wire  cart  or 
wagon  is  damaged,  the  chief  of  section,  with  the  necessary 
number  of  men,  remains  with  it  until  repaired,  unless  the 
damage  is  beyond  repair. 

Special  attention  should  be  paid  to  the  rate  of  march.  It 
is  greater  for  trained  than  for  untrained  troops ;  for  small 
commands  than  for  large  ones;  for  lightly  burdened  than  for 
heavily  burdened  troops.  It  is  greater  during  cool,  than  during 
hot  weather.  Highly  trained  troops  seldom  march  at  a  rate 
greater  than  from  2^4  to  3  miles  per  hour. 

Closing  up  during  a  halt,  or  changing  gait  to  gain  or  lose 
distance  should  be  prohibited. 

CAMPING  ON  THE  MARCH 

Camping,  while  on  the  march,  is  in  line,  column  of  platoons, 
or  sections,  according  to  the  nature  of  the  available  camping 
space.  The  company  is  formed  as  desired,  with  proper  inter- 
vals of  distances,  and  the  platoons  or  sections,  as  the  case 
may  be,  turned  over  to  the  chiefs  of  the  units  into  which  the  camp 
is  established. 

The  wagons  are  parked  with  about  15  yards  interval,  on 
the  most  convenient  flank.  The  wagons  of  the  train  are 
parked  in  a  similar  manner  15  yards  in  rear  of  them.  The  sec- 
tion picket  lines  are  carried  on  the  carts.  While  the  men  indi- 
vidually mounted  are  unsaddling  the  other  men  attach  the 


POIXTERS  OX  MARCHING 


523 


picket  lines.  The  horses  of  each  section  are  tied  in  the  space 
between  the  carts,  commencing  with  the  first  section.  This 
work  is  supervised  by  the  company  commander. 

The  harness  is  placed  on  the  footboards  and  covered  with 
the  paulins  used  for  protecting  carts  and  instruments.  Saddles 
are  placed  alongside  the  tongues  under  the  paulins,  and  this 
equipment  protected  from  the  weather  by  the  cart  paulins. 

Should  it  become  necessary  to  camp  in  the  road,  the  shelter 
tents  can  be  placed  to  one  side  in  line  and  the  picket  line 
extended  from  one  flank.  The  officers'  tents  are  placed  in  the 
locality  most  available  and  the  kitchen  in  the  most  convenient 
place  for  the  men.  Tents  are  faced  according  to  prevailing 
weather.  Men  not  assigned  to  sections  pitch  tents  with  the 
train. 

On  arriving  in  camp,  sinks  are  dug  at  once.  If  the  march  is 
to  be  resumed  the  following  day,  some  sanitary  arrangement 
may  be  made;  ordinarily  sinks  with  brush  screens  will  be  neces- 
sary. 

Camp  is  broken  in  the  following  order :  Immediately  after 
reveille  the  men  feed  their  horses  and,  if  time  permits,  groom 
for  20  minutes,  each  man  caring  for  his  own  horse. 

Tents  are  struck  and  rolls  made,  which  is  followed  by  break- 
fast, then  water  call,  followed  by  boots  and  saddles.  The  picket 
lines  are  placed  upon  the  carts  and  the  company  formed  in 
column  of  sections  or  as  directed  by  the  captain. 

In  maintaining  extended  lines,  the  men  camp  in  pairs,  squads, 
or  sections,  as  the  nature  of  the  duty  dictates. 

For  camps  of  any  duration,  or  permanent  camps,  instruc- 
tions contained  in  "Field  Service  Regulations"  will  be  followed; 


FIELD  LINES 

GENERAL    PROVISIONS 

From  instruction  with  the  buzzer  the  work  will  be  carried 
on  in  actually  laying  field  lines  on  the  drill  ground  or  along 
such  roads  as  are  available.  The  units  for  this  work  will  be 
the  section,  platoon,  and  company.  Whether  operating  alone 
or  in  combined  training  each  section  lays,  operates,  and  main- 
tains its  own  line. 

Two  kinds  of  wire  are  provided  for  this  work:  The  11- 
strand  field  wire,  which  will  be  used  when  possible,  and  the  3- 
strand  buzzer  wire,  which  will  be  used  only  as  hereinbefore 
prescribed. 

THE  WIRE  CART 

The  means  provided  for  laying  field  lines  is  a  wire  cart, 
with  drums  and  an  automatic  gear  for  picking  up  the  wire 
when  driving  back  over  the  line.  This  is  supplemented  by 
carriers  for  buzzer  wire  to  be  used  by  men  on  foot  or  mounted. 

Immediately  after  each  drill,  maneuver,  or  other  formation, 
the  wire  cart  will  be  thoroughly  inspected  by  the  chief  of 
section.  Notes  will  be  made  of  necessary  repairs,  and  turned 
in  by  him  to  the  company  commander.  An  inspection  will  be 
made  prior  to  each  formation  by  the  chief  of  section,  to  see 
that  all  the  bearings  of  the  cart  are  clean  and  oiled,  except  the 
clutch,  which  will  be  bright  and  free  from  oil.  He  will  see 
that  the  axles  are  greased  and  the  harness  in  repair;  that  oil 
cans  are  full,  and  that  there  is  no  sediment  in  the  holes  to 
prevent  the  oil  from  reaching  the  bearings. 

To  CLEAN  THE  WIRE  CART 

Always  after  the  cart  has  been  used,  after  each  formation, 
before  the  cart  is  parked,  the  drivers  and  cart  operators  will 
thorougly  clean  the  chains,  friction  clutch,  and  sprocket  wheels 
with  a  stiff  brush  and  rough  cloth,  removing  all  dust,  dirt,  and 
hard  oil.  After  cleaning,  these  parts  will  be  gone  over  with 
a  well-oiled  cloth  to  prevent  rust. 

524 


FIELD   LINES 


525 


Once  each  week,  or  when  directed  by  the  company  com- 
mander, the  section  will  be  assembled,  and,  under  the  super- 
vision of  the  chief  of  section,  the  cart  given  a  thorough  wash- 
ing and  cleaning  throughout.  All  dirt  and  dust  will  be  removed 
from  the  woodwork  with  a  broom  or  stiff  brush,  and  dust  and 
oil  from  the  metal  parts  with  a  cloth.  Hose  will  then  be  used 
to  wash  the  cart,  if  available;  otherwise  pails  and  sponges  will 
be  used.  The  metal  parts  will  be  wiped  dry  before  oiling. 

Occasionally  the  friction  clutch  will  be  taken  apart  under  the 
supervision  of  the  chief  of  section  and  cleaned  with  gasoline.  A 
light  oil  will  be  sparingly  used  before  assembling  to  prevent 
rust. 


THE   WIRE   CART   SHOWING,   IN   THE   SHADOW   UNDERNEATH 

THE    SEAT,    THE    DRUMS  WHICH   CARRY   THE   WIRE 

FOR    FIELD     COMMUNICATION 


In  the  field  paulins  will  be  placed  over  the  carts  after  use. 
and  not  removed  until  the  cart  is  again  used.  These  paulins 
will  be  folded  and  placed  on  the  chest  when  the.  cart  is  in 
action. 


526  MILITARY  SIGNAL  CORPS  MANUAL 

MANIPULATION  OF  THE  WIRE  CART 

The  manipulation  of  the  machinery  of  the  cart  for  handling 
wire  will  be  a  part  of  the  duty  of  the  cart  driver,  unless  an 
operator  be  placed  on  the  cart,  in  which  case  the  latter  will  do 
this.  He  will  stop  the  cart  at  command  or  signal  from  the  chief 
of  section. 

The  reel  will  always  be  stopped  before  a  march  to  the  rear  is 
taken  up. 

In  spooling  up  wire  the  reel  should  be  stopped  when  the 
loop  gets  too  short  and  the  clutch  should  be  thrown  in  before 
the  loop  gets  too  long. 

LAYING  THE  LINES 

Slack  will  be  pulled  back  and  the  wire  tied  in  every  500  or 
600  yards,  or  when  the  section  chief  directs.  The  line  will 
always  be  tied  at  turns,  in  such  manner  as  to  prevent  the  wire 
from  crossing  the  roads.  Under  no  circumstances  will  the 
wire  be  so  tied  as  to  subtend  the  arc  formed  by  any  turn  in 
the  road.  Should  a  number  of  turns  come  together,  the  cart 
will  be  halted  until  the  work  is  satisfactorily  performed.  Ties 
will  be  made  by  two  round  turns  and  a  half  hitch,  around 
bushes,  trees,  or  anything  fixed  in  the  ground,  and  as  close  to 
the  ground  as  possible. 

At  points  where  the  line  crosses  roads  or  at  crossroads  the 
line  will  be  raised  overhead  or  buried,  unless  the  road  is  little 
traveled,  when  it  may  be  tied  on  each  side  with  plenty  of 
slack.  When  there  is  nothing  to  tie  to,  stones  will  be  placed  on 
the  wire  on  either  side  of  the  road. 

Generally  the  wire  will  be  laid  to  one  side  of  the  roadbed 
to  avoid  unnecessary  damage  to  the  wire  from  wheels,  etc., 
but  in  unfenced  country,  where  mounted  men  and  stock  may  ap- 
proach the  road  from  the  adjacent  fields,  it  will  frequently  be 
advisable  to  lay  it  in  the  road,  so  that  it  will  be  flat  and  also  be 
more  easily  seen. 

Plenty  of  slack  wire  always  will  be  taken,  so  that  it  will 
drop  off  the  feet  of  animals  passing  over  it,  without  breaking 
the  wire  or  throwing  the  animal. 

In  crossing  railroads  or  trolley  lines,  the  wire  is  cut  and  the 
ends  run  under  the  rails.  To  prevent  delay,  a  man  of  the  sec- 
tion will  be  dropped  off  at  such  crossings  and  connect  the  wire, 
then  overtake  the  section  at  an  increased  gait. 

To  repair  a  break  the  ends  will  be  first  scraped,  the  scraped 
ends  tied  in  a  square  knot,  the  loose  ends  twisted  around  the 
line  wire,  and  all  carefully  insulated  with  tape.  The  knots 


FIELD   I.l.VES 


527 


should  be  pulled  tight  and  made  as  small  as  possible,  so  that 
in  reeling  up  the  knots  will  not  jerk  the  pike  and  glove  from 
the  hand. 

Lines  which  have  been  hastily  laid  will  be  patrolled  at 
once,  the  linemen  proceeding  from  each  end  until  they  meet, 
reporting  from  there  by  wire  to  their  sections  for  instructions. 
In  thus  patrolling  the  lines  it  will  be  with  a  view  to  placing  the 
wire  flat  on  the  ground,  should  it  have  become  taut  after  the 
section  passed,  and  otherwise  arranging  it  to  lessen  the  likeli- 
hood of  breaks.  Should  a  line  cross  a  macadamized  road, 
heavily  traveled  by  artillery  and  cavalry,  with  no  means  to 


PHOTOGRAPH  TAKEN  DURING  THE  PROGRESS  OF  AN 

ENGAGEMENT  IN  THE  GREAT  WAR,  SHOWING 

ITALIAN   SIGNAL  TROOPS   WITH   PIKES 

AND  A  WIRE  CARRIER,  ABOUT  TO 

LAY    A    FIELD    LINE 

place  it  overhead,  a  lineman  will  be  left  at  the  point  to  repair 
any  possible  break.  Should  travel  over  the  road  practically 
cease,  he  will  ask  for  instructions  by  wire. 

Frequent  patrols  will  be  made  over  lines  which  pass  over 
fields  of  grain,  weeds,  or  underbrush  in  unfenced  country,  and 
can  neither  be  placed  flat  on  the  ground  nor  overhead.  Breaks 
are  more  apt  to  occur  with  lines  thus  laid. 


528  MILITARY  SIGNAL  CORPS  MANUAL 

On  all  occasions  in  handling  wire,  such  as  reeling  it  on  to 
the  reels  in  filling  them  or  reeling  it  off  for  repairs,  the  section 
chief  will  have  leaks  in  insulation  repaired  and  all  connections 
looked  over.  This  aids  materially  in  the  working  of  the  lines 
when  the  wire  is  laid. 

MANEUVERS  OF  THE  BATTALIONS 

Wire  will  not  be  picked  up  at  a  faster  gait  than  a  trot. 
Should  a  more  rapid  gait  become  necessary  to  escape  capture, 
the  wire  will  be  cut  and  abandoned.  The  real  object  is  to  lay 
wire  and  not  to  pick  it  up.  Should  wire  have  to  be  abandoned, 
the  cart  will  refill  its  reel  at  the  earliest  possible  moment  from 
the  reserve.  Wire  will  only  be  temporarily  abandoned  at  ma- 
neuvers. The  section  will  return  for  it  when  the  maneuver  is 
completed.  Under  no  circumstances  will  wire  be  reeled  up  on 
the  reels  or  spools  until  any  breaks  in  the  metallic  continuity 
of  the  wire  have  been  repaired. 

In  passing  through  villages,  the  wire  will  be  placed  overhead 
on  telegraph  and  telephone  poles.  The  climbers  carried  with 
the  cart  will  be  used  for  this  purpose.  A  man  will  be  dropped 
for  this  work;  when  completed,  he  overtakes  the  section.  Men 
left  behind  in  laying  the  wire,  for  any  duty,  will  follow  the  line 
in  overtaking  the  section,  looking  for  breaks. 

The  gait  to  be  taken  in  laying  lines  will  depend  on  the  kind 
of  troops  the  section  is  following  and  the  speed  made  by  them. 
In  all  cases  the  line  will  keep  in  touch  with  the  element  it  is 
to  transmit  information  for.  When  the  last  station  is  cut  in, 
horses  may  be  unhitched  if  the  troops  seem  likely  to  remain 
in  place  any  length  of  time. 

On  the  care  with  which  lines  are  laid  will  depend  in  no 
small  degree  their  efficiency.  Carelessly  laid  lines  will  need 
much  attention  to  repair  breaks,  and  will  cause  many  delays  in 
messages,  and  no  end  of  annoyance  to  other  troops. 

Speed  will  always  be  sacrificed  to  carefulness  in  this  work. 
Wire  fences,  telephone  and  telegraph  lines  may  sometimes  be 
used  to  advantage. 

STATIONS  AND  CAIL  LETTERS 

Each  section  will  be  assigned  call  letters  for  four  stations, 
which  in  general  should  not  exceed  four.  The  first  section 
will  be  given  the  letters  A,  B,  C,  and  D;  the  second  section 
the  letters  F,  G,  H,  and  K;  the  third  section  M,  N,  Q,  and  R; 
the  fourth  section,  S,  U,  W,  and  X.  The  stations  are  assigned 
to  call  letters  in  order  of  establishment,  not  location,  begin- 
ning with  the  first  letters.  The  call  of  headquarters  is  KO, 


FIELD  LINES 


520 


w.hich  will  be  its  call  whenever  it  may  be  on  the  line,  suspending 
for  the  time  being  the  letter  of  the  station  where  it  may  be. 
This  applies  to  the  first  station  established  as  well  as  to  the 
later  ones. 

Branch  lines  electrically  connected  with  the  main  line  have 
offices  given  calls  as  if  on  the  main  line. 

An  office  on  a  branch  line  not  connected  with  the  main  line 
will  be  assigned  the  call  letters  of  the  station  where  the  branch 
goes  out,  adding  J  to  it. 

As  soon  as  a  station  is  established  the  operator  will  call  up 
the  initial  station  and  report.  The  opening  of  all  stations,  in- 
cluding the  initial  station,  will  be  reported  to  the  officer  or  non- 
commissioned officer  in  charge  of  the  line,  and  by  the  latter 
to  the  company  commander  and  to  the  commanding  officer  for 
whose  use  the  line  was  established. 


A    FIELD   WIRE    STATION    OPEN    AND   IN    OPERATION    UNDER 
ACTUAL   SERVICE   CONDITIONS 

Each  operator  will  have  a  personal  sign,  as  Smith  "SM," 
Johnson  "JO,"  etc. 

To  open  station  with  buzzer  the  operator  will  attach  the 
buzzer  connector  to  the  line  wire  and  ground  rod.  Care  will 
be  taken  that  the  teeth  of  the  connector  have  penetrated  the 
insulation  of  the  line  wire.  Damp  ground  will  be  sought  for 
the  ground  rod;  if  not  available  the  ground  will  be  dampened 
around  it  with  water  from  the  canteen. 


530  MILITARY  SIGNAL  CORPS  MAXi'AL 

The  operators  will  not  leave  their  buzzers  unless  properly  re- 
lieved by  higher  authority. 

At  night,  when  lanterns  are  necessary  at  a  station,  the  light 
must  be  so  placed  as  to  conceal  it  from  hostile  observation. 

When  it  becomes  necessary  to  mov»  a  station  some  distance 
from  the  line  and  it  is  not  practicable  to  use  field  wire  for 
extending  the  line,  the  buzzer  carried  by  the  lineman  may  be 
used. 

The  buzzer  carried  by  the  lineman  may  be  used  for  opening 
stations  on  branch  lines. 

Stations  will  be  conducted  in  a  military  manner.  Silence 
will  be  preserved,  except  conversation  relative  to  business. 
The  lines  will  not  be  used  for  conversational  purposes  between 
operators. 

Buzzers  will  be  kept  dry.    In  case  of  wet  weather  the  shelter 
tents  of  messenger  and  operator  will  be  made  into  an  office. 

No  unauthorized  person  will  be  allowed  around  stations. 

MAINTAINING  THE  LINES 

Each  lineman  will  be  equipped  with  a  carrier  with  one- 
fourth  mile  buzzer  wire  and  a  buzzer  for  testing  the  line.  This 


THE    WIRE    PIKE    USED    IN    LAYING    FIELD    LINES 


will  enable  linemen  to  determine  in  what  part  of  the  line  a 
break  may  be.  Intermediate  stations  will  assist  in  this,  and 
when  the  section  in  which  the  break  exists  has  been  located  the 
messenger  or  any  available  man  will  be  sent  to  find  and  repair 
it  if  no  lineman  is  at  hand.  In  following  the  line  to  locate 
breaks  the  lineman  will  take  up  the  gallop,  following  the  line 
with  his  eye  where  it  is  raised  from  the  ground,  and  with  the 
pike  where  it  is  on  the  ground.  He  picks  it  up  with  the  hook. 
In  order  to  prevent  a  knot  or  splice  from  being  caught  in  the 
hook  and  jerking  the  pole  from  his  hand  he  raises  the  pike  in  a 
horizontal  position,  slips  the  wire  out  of  the  hook  and  on  to  the 
handle,  and  allows  the  wire  to  run  on  it  near  the  hook,  the 
shoulder  of  the  hook  keeping  it  from  slipping  off.  By  lowering 
the  pike  and  turning  it  around  in  the  hand  the  wire  slips 
quickly  to  the  ground. 


CAMPS 

There  are  two  general  classes  of  camps ;  semi-permanent 
camps  and  temporary  camps. 

Semi-permanent  camps  are  used  for  troops  in  mobilization, 
concentration,  or  maneuver  camps,  and  during  such  pauses 
in  operations  as  permit  the  better  care  of  troops. 

Temporary  camps  are  used  on  the  march  or  during  opera- 
tion when  halts  are  made  only  for  the  night  or  for  a  few  days 
at  most. 

SEMI-PERMANENT  CAMPS 

GENERAL 

Semi-permanent  camps  contemplate  the  use  of  pyramidal  and 
wall  tents,  mess  shelters,  baths,  latrines,  raised  picket  lines 
on  substantial  posts,  and  corrals  when  practicable.  The  equip- 
ment therefor  is  classed  as  Equipment  "B",  and  is  not  carried 
on  division  trains,  but  when  required  is  brought  up  by  other 
transportation. 

The  forms  and  dimensions  of  semi-permanent  camps  and 
the  character  and  amount  of  tentage  or  other  shelter  used  vary 
greatly  with  the  conditions. 

Every  effort  must  be  made  to  provide  adequate  shelter  for 
both  men  and  animals. 

Animals  constantly  exposed  to  the  sun  in  hot  weather  and 
to  cold  winds,  rain,  or  snow  in  winter  lose  condition  very 
rapidly. 

Suitable  tents  or  other  shelter  must  be  provided  for  work- 
shops for  mechanics  and  for  kitchens.  Condemned  canvas 
can  be  utilized  for  these  purposes  in  camps  of  a  duration  too 
short  to  justify  suitable  buildings. 

531 


532  MILITARY  SIGNAL  CORPS  MANUAL 

When  the  camp  is  reached  by  rail  the  timbers  used  in  secur- 
ing the  carriages  on  the  cars  are,  if  carefully  removed,  very 
convenient  for  such  purposes. 

The  detailed  arrangements  of  the  normal  semi-permanent 
camps  are  given  in  the  illustration.  Whenever  practicable  the 
width  of  the  camps  therein  shown  should  be  somewhat  ex- 
tended. 

The  picket  line  should  be  well  drained  by  cutting  ditches 
about  12  feet  on  either  side  of  the  line  and  throwing  tht 
earth  to  the  center.  Whenever  practicable  the  ground  should 
be  covered  with  broken  stone,  sand,  or  cinders.  Particular 
care  must  be  taken  to  provide  dry  footing  not  only  on  the 
picket  line  but  around  the  watering  places  in  semi-permanent 
camps. 

The  requirements  which  semi-permanent  camp  sites  should 
fulfill  are  given  in  Field  Service  Regulations.  • 

In  semi-permanent  camps  guard  and  other  duties  follow 
closely  the  custom  in  garrison. 

The  camp  is  policed  daily  after  breakfast  and  all  refuse 
burned.  Tent  walls  are  raised  immediately  after  breakfast 
and  the  bedding  and  clothing  aired  daily,  weather  permitting. 

SHELTER  TENT  CAMPS 


The  shelter  tent  or  temporary  camp  is  used  in  the  field 
when  halts  are  not  to  be  of  sufficient  duration  to  justify  the 
bringing  up  of  semi-permanent  camp  equipage,  or  when  same 
is  not  available.  They  will,  of  necessity,  vary  greatly  in  form, 
dimensions  and  area  occupied  and  in  the  means  available  for 
the  improvisation  of  camping  expedients.  The  regulations 
and  plates  hereinafter  prescribed  are  given  as  conforming  to 
usual  conditions  and  should  govern  in  all  instruction  in  the 
selection  and  occupation  of  shelter-tent  camp  sites.  In  actual 
service  the  dispositions  in  camp  must  be  adapted  to  the  ground 
and  must  be  made  so  as  to  derive  the  maximum  benefit  from 
the  meager  camp  equipment  carried.  The  camp'  will  in  this 
latter  instance,  therefore,  seldom  be  ideally  regular.  When- 
ever possible,  battalions,  companies,  and  platoons  should  be 
camped  in  column  of  sections  (in  outpost  companies,  column  of 
platoons).  The  principal  advantage  accruing  in  camping  in 
columns  is  the  freedom  afforded  for  withdrawing  independent 
sections  from  camps  when  it  is  desired  to  send  them  on  de- 
tached missions. 


si     i        T-      T      T 

^.^•jsy.-^ if^^-j^^as^ 

flCLD  BATTAUON 


"TafiSRAPH  BAlTAiJON" 


•  * 

i 


oT»i^cT*»4'  n*^-»-  i<*»vj 


ARRANGEMENT  OF   SEMI- PERMANENT    CAMP 
533 


534  MILITARY  SIGNAL  CORPS  MANUAL 

Even  in  small  commands,  the  commanding  officer,  or  an 
officer  designated,  should  precede  the  column  to  look  over  the 
camping  ground  and  decide  on  the  arrangement  of  the  camp, 
so  that  on  the  arrival  the  command  may  immediately  occupy 
the  ground  assigned  it  and  commanders  may  be  promptly  in- 
formed as  to  arrangement  for  water,  fuel,  forage,  and  rations. 

THE   SELECTION    OF   SHELTER  TENT  CAMP  SITES 

In  campaign,  tactical  necessity  may  leave  little  choice  in 
the  selection  of  camp  sites,  but  under  any  conditions  the  re- 
quirements of  sanitation  should  be  given  every  consideration 
consistent  therewith. 

In  general,  the  following  principles  govern : 

The  site  should  be  convenient  to  an  abundant  supply  of 
pure  water. 

Good  roads  should  lead  to  the  camp.  Interior  communica- 
tion throughout  the  camp  should  be  easy.  A  camp  near  a 
main  road  is  undesirable  on  account  of  dust  and  noise. 

Wood,  grass,  forage,  and  supplies  should  be  at  hand  or 
easily  obtainable. 

The  ground  should  accommodate  the  command  without 
crowding  and  without  compelling  the  troops  of  one  unit  to 
pass  through  the  camp  of  another. 

The  site  should  be  sufficiently  high  and  rolling  to  drain 
off  storm  water  readily,  and,  if  the  season  be  hot,  to  face  the 
breeze.  In  cold  weather  it  should  preferably  have  a  south- 
ern exposure,  with  woods  to  break  the  prevailing  winds.  In 
warm  weather  an  eastern  exposure,  with  the  site  moderately 
shaded  by  trees,  is  desirable. 

The  site  should  be  dry.  For  this  reason  porous  soil,  cov- 
ered with  stout  turf  and  underlaid  by  a  sandy  or  gravelly  sub- 
soil is  best.  A  site  on  clay  soil,  or  where  the  ground  water 
approaches  the  surface,  is  damp  and  unhealthful. 

Alluvial  soils,  marshy  ground,  and  ground  near  the  base  of 
hills  or  near  thick  woods  or  dense  vegetation  are  undesirable 
as  camp  sites  on  account  of  dampness.  Ravines  and  depres- 
sions are  likely  to  be  unduly  warm  and  to  have  insufficient 
or  undesirable  air  currents. 

Proximity  to  marshes  or  stagnant  water  is  undesirable  on 
account  of  the  dampness  and  mosquitoes  and  the  diseases 
which  the  latter  transmit.  The  high  banks  of  lakes  or  large 
streams  often  make  desirable  camp  sites. 

Dry  beds  of  streams  should  be  avoided;  they  are  subject  to 
sudden  freshet. 

The  occupation  of  old  camp  sites  is  dangerous,  since  these 
are  often  permeated  by  elements  of  disease  which  persist  for 


CAMPS  535 

considerable  periods.  Camp  sites  must  be  changed  promptly 
when  there  is  evidence  of  soil  pollution  or  when  epidemic 
disease  threatens,  but  the  need  for  frequent  changes  on  this 
account  may  be  a  reflection  on  the  sanitary  administration  of 
the  camp. 

A  change  of  camp  site  is  often  desirable  in  order  to  secure 
a  change  of  surroundings  and  to  abandon  areas  which  have 
become  dusty  and  cut  up. 

THE    FIELD    BATTALION    CAMP 

The  field  battalion,  or  any  fraction  thereof,  will  normally 
camp  in  accordance  with  the  accompanying  drawing. 

Occupation  of  Camp  Site 

The  command  is  normally  conducted  from  left  to  right  along 
the  rear  of  the  plot  selected  for  the  camp  site.  The  location 
of  the  camp  site,  of  the  leading  section  of  the  leading  com- 
pany is  indicated  to  the  captain  of  that  company  and  the  com- 
mand 1.  By  company,  2.  At  camping  interval,  3.  LEFT  INTO 
LINE  is  given.  The  captain  of  each  company  commands:  1.  At 

yards  interval,  2.  Left  into  line,  adding  3.  MARCH,  at  a 

time  so  that  the  leading  section  of  the  company  in  executing 
the  movement  ordered  will  find  itself  marching  to  the  left 
over  the  ground  to  be  occupied  by  the  section  picket  line  and 
with  the  center  of  the  section  in  prolongation  of  the  line  of  the 
front  of  the  section  line  of  shelter  tents  to  be  established.  In 
giving  the  preparatory  commands  for  forming  left  into  line, 
each  captain  announces  such  interval  as  will  give  an  interval 
of  8  yards  between  section  picket  lines  when  they  are  secured 
in  prolongation  of  the  center  line  of  the  sections,  and  gives  the 
command  of  execution  so  that  his  right  section  picket  line 
will  be  16  yards  from  the  left  picket  line  of  the  company  on  the 
right.  For  the  company  on  the  left  of  the  outpost  company 
this  distance  will  be  increased  to  24  yards. 

Each  captain  halts  his  company  when  the  rear  of  the  lead- 
ing section  has  reached  a  point  4  yards  in  advance  of  where 
the  front  pin  of  the  section  picket  line  is  to  be  placed.  The 
remaining  sections  halt  with  the  rear  elements  aligned  on  that 
of  the  right  section. 

When  the  command  is  halted  and  rear  elements  aligned,  the 
command  MAKE  CAMP  is  given.  Each  captain  commands 
SECURE  PICKET  LINES.  At  this  command,  each  chief  of 
section  takes  charge  of  his  section,  causes  the  men  to  dis- 
mount and  turn  animals  over  to  horseholders.  The  section 
picket  line  is  then  secured,  the  front  picket  pin  being  placed 


A  FIELD  BATTALION   SHELTER  TENT  CAMP 

536 


CAMPS  537 

4  yards  directly  in  rear  of  the  center  of  the  section  and  the 
rear  pin  50  feet  therefrom  and  in  such  a  position  that  the 
picket  line,  when  tightened,  v/ill  be  in  continuation  of  the  line 
formed  by  the  front  of  the  section  line  of  shelter  tents  to-bt 
established  and  the  tongue  of  the  wire  cart  or  the  front  edge 
of  the  aparejo  park. 

The  wagon  radio  section  and  the  platoons  of  the  outpost 
company  camp  in  two  lines  as  indicated.  The  battalion  and 
company  lines  are  secured  simultaneously  and  in  a  like  man- 
ner by  the  appropriate  personnel. 

After  section  lines  and  the  company  line  have  been  secured 
as  above  each  captain  commands  :  TIE  TO  THE  LINE.  Wire 
carts  are  unhitched  and  harness  removed  and  disposed  as  be- 
fore prescribed,  bridles  are  removed  from  pack  and  riding 
animals,  and  all  animals  are  tied  to  the  line.  Girths  are  loos- 
ened on  pack  and  riding  animals,  saddles  being  left  on  until 
the  backs  are  cooled.  One  or  two  men  are  left  at  each  picket 
line  at  this  time  to  watch  animals  and  prevent  them  from 
lying  down  or  rolling.  Where  no  company  lines  are  pro- 
vided, company  headquarters  combat  animals  are  distributed 
among  section  lines  to  the  best  advantage.  Field-train  animals 
except  those  drawing  ration  vehicles  are  tied  to  their  wagons. 
Each  section,  less  temporary  picket-line  guard,  is  formed  in 
two  ranks  dismounted,  as  prescribed  for  forming  the  squad,  fac- 
ing to  the  right  or  left,  as  indicated,  with  the  chief  of  section 
(in  platoons  of  the  outpost  company,  the  assistant  platoon  chief) 
on  the  right  (left)  of  the  front  rank  directly  in  front  of  the 
section  picket  line  and  about  13  yards  from  the  front  picket 
pin.  Assistant  platoon  chiefs  in  the  outpost  company  and  the 
chief  of  the  wagon  radio  section  take  post  on  the  right  (left) 
of  the  front  line  of  their  sections.  Men  carry  their  blanket 
roll,  saddlebags,  canteens,  and  haversacks. 

The  chief  of  each  section  then  causes  his  section  to  take 
interval  to  the  left  (right)  as  prescribed  for  the  Squad  and 
commands:  PITCH  TENTS.  As  each  man  faces  to  the  front  he 
places  his  blanket  roll  and  other  equipment  on  the  ground. 
Members  of  the  company  and  battalion  staff  not  grouped  into 
a  provisional  section  pitch  tents,  and  wagon  transportation 
is  disposed  as  indicated  in  the  plate.  Drivers  of  instrument, 
shop,  and  field  train  wagons  sleep  in  or  under  them. 

After  tents  are  pitched  sections  return  to  picket  lines,  un- 
saddle the  animals,  take  individual  saddle  equipment  to  the 
tents,  and  arrange  the  aparejos  and  other  equipment  in  park. 

Wood,  water,  and  the  necessary  guard  and  fatigue  details 
assume  their  duties. 


TELEGRAPH  BATTALION  SHELTER  TENT  CAMP 
538 


CAMPS  539 

THE    TELEGRAPH     BATTALION'     CAMP 

The  telegraph  battalion,  or  any  fraction  thereof,  will  norm- 
ally camp  in  accordance  with  the  accompanying  drawing. 

Occupation  of  Camp  Site 

The  telegraph  battalion  will  conform  as  nearly  as  prac- 
ticable to  the  means  and  methods  prescribed  for  the  field  bat- 
talion in  the  occupation  of  camp  sites 

TO   PITCH    SHELTER    TENTS 

At  the  command  PITCH  TENTS  the  men  open  their  blanket 
rolls  and  take  out  the  shelter  half,  poles  and  pins;  the  front 
man  places  one  pin  in  the  ground  at  the  point  where  his 
right  heel,  kept  in  position  until  this  time,  was  planted.  Each 
then  spreads  his  shelter  half,  triangle  to  the  rear,  flat  upon 
the  ground  the  tent  is  to  occupy,  rear  man's  half  on  the  right. 
The  halves  are  then  buttoned  together.  Each  front  man  joins 
his  pole,  inserts  the  top  in  the  eyes  of  the  halves,  and  holds 
the  pole  upright  beside  the  pin  placed  in  the  ground;  his  rear 
rank  man,  using  the  pin  in  front,  pins  down  the  front  corners 
of  the  tent  on  the  line  of  pins,  stretching  the  canvas  taut;  he 
the  inserts  a  pin  in  the  eye  of  the  rope  and  drives  the  pin  at 
such  distance  in  front  of  the  pole  as  to  hold  the  rope  taut. 
Both  then  go  to  the  rear  of  the  tent;  the  rear  rank  man  adjusts 
the  pole  and  the  front  rank  man  drives  the  pins.  The  rest  of 
the  pins  are  then  driven  by  both  men,  the  rear  rank  man  work- 
ing on  the  right. 

The  guy  ropes,  to  have  a  uniform  slope  when  the  shelter 
tents  are  pitched,  should  all  be  of  the  same  length. 

TO   STRIKE   SHELTER   TEXTS 

The  men  standing  in  front  of  their  tents :  Strike  tents. 
Equipments  are  removed  from  the  tents ;  the  tents  are  lowered, 
rolls  made  up,  equipments  slung,  and  the  men  stand  at  atten- 
tion  in  the  places  originally  occupied  after  taking  intervals. 

DOUBLE    SHELTER    TENTS 

The  double  shelter  tent  is  formed  by  buttoning  together 
the  square  ends  of  two  single  tents.  Two  complete  tents,  ex- 
cept one  pole,  are  used.  Two  guy  ropes  are  used  at  each  end, 
the  guy  pins  being  placed  in  front  of  the  corner  pins. 


540  MILITARY  SIG\'AL  CORPS  MAXVAL 

The  double  shelter  tents  are  pitched  by  Nos.  1  and  2  front 
and  rear  rank,  and  by  Nos.  3  and  4,  front  and  rear  rank ;  the 
men  falling  in  on  the  left  are  numbered,  counting  off  if  neces- 
sary. 

The  same  commands  are  given  as  before  for  taking  inter- 
vals, and  the  command  PITCH  DOUBLE  TENTS  is  given. 

Only  the  odd  numbers  of  the  front  rank  mark  the  line  with 
the  tent  pin. 

All  the  men  spread  their  shelter  halves  on  the  ground  the 
tent  is  to  occupy.  Those  of  the  front  rank  are  placed  with 
the  triangular  ends  to  the  front.  All  four  halves  are  then  but- 
toned together,  first  the  ridges  and  then  the  square  ends.  The 
front  corners  of  the  tent  are  pinned  by  the  front-rank  men, 
the  odd  number  holding  the  poles,  the  even  number  driving 
the  pins.  The  rear-rank  men  similarly  pin  the  rear  corners. 

While  the  odd  numbers  steady  the  poles,  each  even  number 
of  the  front  rank  takes  his  pole  and  enters  the  tent  where, 
assisted  by  the  even  number  of  the  rear  rank,  he  adjusts  the 
pole  to  the  center  eyes  of  the  shelter  halves  in  the  following 
order:  First,  the  lower  half  of  the  front  tent;  second,  the 
lower  half  of  the  rear  tent;  third,  the  upper  half  of  the 
front  tent;  fourth,  the  upper  half  of  the  rear  tent.  The  guy 
ropes  are  then  adjusted. 

i 

WATER    SUPPLY 

Immediately  on  making  camp  a  guard  should  be  placed 
over  the  water  supply.  If  the  water  be  obtained  from  a  stream, 
places  should  be  designated,  beginning  upstream,  (1)  for  drink- 
ing and  cooking,  (2)  for  watering  animals,  (3)  for  bathing 
and  washing  clothing. 

If  the  stream  be  small,  the  water  supply  may  be  increased 
by  building  a  dam.  Small  springs  may  be  dug  out  and  each 
lined  with  a  gabion,  or  a  barrel  or  box  with  both  ends  removed, 
or  with  stones,  the  space  between  the  lining  and  the  earth 
being  filled  with  puddled  clay.  A  rim  of  clay  should  be  built 
to  keep  out  surface  drainage.  The  same  method  may  be  used 
near  swamps,  streams,  or  lakes  to  increase  or  clarify  the 
water  supply. 

Water  that  is  not  known  to  be  pure  should  be  boiled  20 
minutes;  it  should  then  be  cooled  and  aerated  by  being  poured 
repeatedly  from  one  clean  container  to  another,  or  it  may 
be  purified  by  approved  apparatus  supplied  for  the  purpose. 

Arrangements  should  be  made  for  men  to  draw  water  from 
the  authorized  receptacles  by  means  of  a  faucet.  The  dipping 
of  water  from  the  receptacles  or  the  use  of  a  common  drink- 
ing cup  should  be  prohibited. 


CAMPS  541 

On  the  march,  including  camps,  the  daily  requirements  of 
water  may  be  estimated  at  6  gallons  per  man  or  10  gallons  per 
horse.  In  permanent  or  semi-permanent  camps  the  supply 
should  be  sufficient  to  provide  from  25  to  30  gallons  per  man 
and  15  gallons  per  horse  per  day.  This  supply  should  be  prop- 
erly piped  and  delivered  at  convenient  places  in  each  organi- 
zation camp. 


Camp  kettles  are  hung  on  irons  or  on  a  support  consisting 
of  a  green  pole  lying  in  the  crotches  of  two  upright  posts  of 
the  same  character. 

A  narrow  trench  for  the  fire,  about  1  foot  deep  under  the 
pole,  protects  the  fire  from  the  wind  and  saves  fuel.  A  still 
greater  economy  of  fuel  can  be  effected  by  digging  a  similar 
trench  in  the  direction  of  the  wind  and  slightly  narrower  than 
the  diameter  of  the  kettles.  The  kettles  are  then  placed  on  the 
trench  and  the  space  over  it  and  between  the  kettles  filled  in 
with  stones,  clay,  or  mud,  leaving  the  flue  running  beneath  the 
kettles.  The  draft  can  be  improved  by  building  a  chimney  of 
similar  material  at  the  leeward  end  of  the  flue. 

Four  such  trenches  radiating  from  a  common  central  chim- 
ney will  give  one  flue  for  use  whatever  may  be  the  direction 
of  the  wind. 

A  slight  slope  in  the  flue,  from  the  chimney  down,  provides 
for  drainage  and  improves  the  draft. 

The  lack  of  portable  ovens  can  be  met  by  ovens  constructed 
of  stone  and  covered  with  earth  to  retain  the  heat.  If  no  stone 
is  available,  an  empty  barrel,  with  one  head  out,  is  laid 
on  its  side  and  covered  with  wet  clay  to  a  depth  of  6  or  more 
inches,  and  then  with  a  layer  of  dry  earth  equally  thick.  A 
flue  is  constructed  with  clay  above  the  closed  end  of  the  barrel, 
which  is  then  burned  out  with  a  hot  fire.  This  leaves  a  baked 
clay  covering  for  the  oven. 

A  recess  can  be  similarly  constructed  with  boards,  or  even 
brushwood,  supported  on  a  horizontal  pole  resting  on  upright 
posts,  covered  and  burnt  out  as  in  the  case  of  the  barrel. 

When  clay  banks  are  available,  an  oven  may  be  excavated 
therein  and  used  at  once. 

Tx>.  bake  in  such  ovens,  first  heat  them  and  then  close  flues 
and  ends. 

Food  must  be  protected  from  flies,  dust,  and  sun.  Facilities 
must  be  provided  for  cleaning  and  scalding  the  mess  equip- 
ment  of  the  men.  Kitchens  and  the  ground  around  them  must 
be  kept  scrupulously  clean. 


542  MILITARY  SIGNAL  CORPS  MANUAL 

Solid  refuse  should  be  promptly  burned,  either  in  the  kitchen 
fire  or  in  an  improvised  crematory. 

In  temporary  camps,  if  the  soil  is  porous,  liquid  refuse  from 
the  kitchens  may  be  strained  through  sacking  into  seepage 
pits  dug  near  the  kitchen.  Boards  or  poles,  covered  with  brush 
or  grass  and  a  layer  of  earth  may  be  used  to  prevent  the  ac- 
cess of  flies.  The  strainer  should  also  be  protected  from  flies. 
Pits  of  this  kind  in  clay  soil  will  not  operate  successfully.  All 
pits  should  be  filled  with  earth  when  the  camp  is  abandoned. 

DISPOSAL   OF    EXCRETA 

Immediately  on  arriving  in  camp  sinks  should  be  dug.  This 
is  a  matter  of  fundamental  sanitary  importance,  since  the  most 
serious  epidemics  of  camp  diseases  are  spread  from  human 
excreta. 

One  sink  is  usually  provided  for  each  company  and  one  for 
the  officers  of  each  battalion.  Those  for  the  men  are  invari- 
ably located  on  the  side  of  camp  opposite  the  kitchens.  All 
sinks  should  be  so  placed  that  they  can  not  pollute  the  water 
supply  or  camp  site  as  a  result  of  drainage  or  overflow.  To 
insure  this,  their  localities  and  their  distance  from  camp  may 
be  varied. 

When  camp  is  made  for  a  single  night,  shallow  trenches, 
12  inches  deep  and  15  to  18  inches  wide,  which  the  men  may 
straddle,  will  suffice. 

In  camps  of  longer  duration,  and  when  it  is  not  possible  to 
provide  latrine  boxes,  as  for  permanent  camps,  deeper  trenches 
should  be  dug.  These  may  be  used  as  straddle  trenches  or  a 
seat  and  back  rest  improvised  from  poles  or  other  available 
material.  They  should  be  screened  by  brush,  condemned  canvas, 
or  other  material.  When  open  trenches  are  used,  special  care 
must  be  taken  to  insure  that  all  excreta  is  covered  with  earth, 
lime,  or  ashes  as  soon  as  it  is  deposited. 

In  permanent  or  semi-permanent  camps  special  sanitary 
facilities  for  the  disposal  or  disinfection  of  excreta  will  ordi- 
narily be  provided.  When  trenches  are  used  in  such  camps 
they  should  be  at  least  6  feet  deep  and  12  feet  long  and  not 
more  than  2  feet  wide.  Seats  are  walled  to  the  ground  and 
provided  with  lids  to  keep  flies  from  reaching  the  deposits ; 
urinal  troughs  discharging  into  the  trenches  are  provided.  Each 
day  the  latrine  boxes  are  thoroughly  cleaned,  outside  by  scrub- 
bing and  inside  by  applying  when  necessary  a  coat  of  crude 
oil  or  whitewash.  The  pit  is  burned  out  daily  with  approxi- 
mately 1  gallon  of  crude  oil  and  15  pounds  straw.  When  filled 
to  within  2  feet  of  the  surface,  such  latrines  are  discarded, 
filled  with  earth,  and  their  position  marked. 


(  .IMPS  543 

In  permanent  camps  urine  tubs  should  be  placed  in  the  com- 
pany streets  at  nightfall;  they  are  emptied  after  reveille.  Their 
location  should  be  plainly  marked  thoroughly  and  frequently 
disinfected. 

CARE   OF  TROOPS   AND   ANIMALS 

Lack  of  sufficient  rest  renders  troops  unfit  for  hard  work 
and  diminishes  their  power  of  resisting  disease.  Therefore 
commanders  should  secure  for  the  troops,  whenever  possible, 
their  accustomed  rest. 

The  rules  of  sanitation  must  be  enforced. 

Men  should  not  be  on  damp  ground.  In  temporary  camps 
and  in  bivouac  they  raise  their  beds  if  suitable  material  such 
as  straw,  leaves,  or  boughs  can  be  obtained,  or  use  their  pon- 
chos or  slickers.  In  cold  weather  and  when  fuel  is  plentiful 
the  ground  may  be  warmed  by  fires,  the  men  making  their  beds 
after  raking  away  the  ashes. 

When  troops  are  to  remain  in  camp  for  some  time,  all  un- 
derbrush is  cleared  away  and  the  camp  made  as  comfortable 
as  possible. 

Watering  troughs,  shelter  in  cold  weather  and  shade  in  hot 
are  provided  for  the  animals  if  practicable. 

To  prevent  stampeding  in  camp  it  will  in  most  cases  be 
sufficient  for  the  men  to  go  quietly  among  the  horses  at  the 
first  sign  of  fright  and  speak  to  them.  If  horses  are  stampeded, 
men  should  mount  the  fastest  animals  within  reach,  place  them- 
selves in  front  of  the  herd,  and  conduct  it  back  to  camp.  With 
old  horses  the  sounding  of  stable  call  may  prevent  or  stop  a 
stampede. 

One  of  the  greatest  difficulties  of  mounted  organizations  in 
campaign  is  to  secure  sufficient  long  forage.  On  this  account 
the  greatest  attention  should  be  given  to  grazing  at  every 
opportunity. 

The  horses  are  either  held  on  the  halter  rope,  picketed  on 
the  lariat,  turned  loose  in  inclosed  pastures,  or  if  there  has 
been  opportunity  for  sufficient  training  they  may  be  herded. 

Special  effort  should  be  made  to  give  them  an  hour  or  two 
of  grazing  in  the  morning  while  the  dew  is  on  the  grass  (not 
clover),  especially  if  the  supply  of  hay  at  night  has  been  short, 
and  in  such  cases  they  should  not  be  disturbed  until  the  last 
moment,  time  lost  being  made  up  by  more  rapid  marching. 

Should  the  horses  have  to  be  protected  from  an  enemy,  they 
are  taken  out  to  graze  under  charge  of  an  officer  as  soon  as 
possible  after  camping.  They  are  taken  as  far  as  is  safe,  so  as 
to  keep  the  nearer  grass  for  night.  It  is  occasionally  prac- 
ticable to  arrange  the  camp  so  as  to  use  the  wagons  and 
natural  obstacles  to  inclose  a  space  for  night  grazing. 


544  MILITARY  SIGNAL  CORPS  MANUAL 

Special   attention   should  be   paid   to   the  grooming  of  ani- 
mals and  to  the  condition  of  their  feet  and  backs. 


COMMON  AND  WALL  TENTS 

Four  men,  numbered  from  1  to  4,  consecutively,  pitch  each 
tent. 

Nos.  1  and  2  place  the  ridgepole  perpendicular  to  the  com- 
pany street,  with  one  end  against  the  position  pin;  Nos.  3  and 
4  drive  a  pin  at  the  other  end  of  the  ridgepole.  Nos.  1  and  2 
mark  the  positions  of  the  four  corner  guy-rope  pins  by  placing 
the  ridgepole  parallel  to  the  company  street,  to  the  right  (fac- 
ing the  tent)  of  the  position  pin;  Nos.  3  and  4  drive  a  large  pin 
one  pace  in  front  of  the  outer  end  of  the  ridgepole.  The  other 
three  corner  guy  pins  are  set  in  succession  in  the  same  manner, 
going  first  straight  to  the  rear,  then  across  the  tent,  and  then 
to  the  front.  All  four  then  spread  the  tent  on  the  ground  it  is 
to  occupy;  Nos.  1  at  the  front  and  2  at  the  rear  insert  the 
uprights.  The  ridgepole  and  uprights  are  joined,  the  pole  pins 
inserted  in  the  eyelets  of  the  tent  and  fly,  and  the  tent  raised 
to  a  vertical  position  with  the  poles  at  the  pins.  Nos.  1  and  2 
hold  the  tent  in  position;  No.  3  places  the  front  guy  ropes  of 
tent  and  fly,  No.  4,  the  rear,  on  their  pins,  and  tighten  the 
ropes  so  as  to  hold  the  poles  vertical.  The  wall  pins  are  then 
driven  through  the  loops,  walls  hanging  vertically.  The  other 
pins  are  then  driven  on  line  with  the  corner  pins  and  in  pro- 
longation of  the  seams  of  the  tent. 


CONICAL  WALL  TENTS 

The  conical  wall  tent  is  pitched  by  eight  men.  The  ranking 
noncommissioned  officer  numbers  the  men  from  1  to  7  and 
superintends  the  work.  Upon  the  hood  lines  of  the  tent  are 
placed  three  marks;  the  first  about  8  feet  3  inches,  the  second 
about  11  feet  3  inches,  the  third  about  14  feet  2  inches  from  the 
hood  ring;  the  first  marks  the  distance  from  the  center  to  the 
wall  pins,  the  second  to  the  guy  pins,  and  the  distance  between 
the  second  and  third  is  the  distance  between  guy  pins.  These 
distances  vary  slightly  for  different  tents  and  should  be  verified 
by  actual  experiment  before  permanently  marking  the  ropes. 
They  should  also  be  frequently  verified  on  account  of  the 
stretching  of  the  rope.  To  locate  the  position  of  guy  pins  after 
the  first,  the  hood  being  held  on  the  center  pin,  with  the  left 
hand  hold  the  outer  mark  on  the  pin  last  set,  with  the  right 
hand  grasp  the  rope  at  the  center  mark  and  move  the  hand  to 


CAMPS  545 

the  right  so  as  to  have  both  sections  of  the  rope  taut;  the  cen- 
ter mark  is  then  over  the  position  desired;  the  inner  mark  is 
over  the  position  of  the  corresponding  wall  pin. 

To  pitch  the  tent,  No.  1  places  the  tent  pole  on  the  ground, 
socket  end  against  the  door  pin,  pole  perpendicular  to  the  com- 
pany street.  No.  2  drives  the  center  pin  at  the  other  extremity 
of  the  pole.  No.  3  drives  a  wall  pin  on  each  side  of  and  1  foot 
from  the  door  pin.  No.  4  places  the  open  tripod  flat  on  the 
ground  with  its  center  near  the  center  pin.  The  whole  party 
then  places  the  tent,  fully  opened,  on  the  ground  it  is  to  occupy, 
the  center  at  the  center  pin,  the  door  at  the  door  pin. 

The  noncommissioned  officer  in  charge  holds  the  hood  ring 
on  the  center  pin,  and  superintends  from  that  position.  No.  1 
stretches  the  hood  rope  over  the  right  (facing  the  tent)  wall 
pin  and  No.  2  drives  the  first  guy  pin  at  the  middle  mark.  No. 
1  marks  the  position  of  the  guy  pins  in  succession  and  No.  2 
drives  a  pin  lightly  in  each  position  as  soon  as  marked.  At  the 
same  time  No.  5  inserts  small  pins  in  succession  through  the 
wall  loops  and  places  the  pins  in  position  against  the  inner 
mark  on  the  hood  rope,  where  they  are  partly  driven  by  No.  6. 
No.  4  distributes  large  pins  ahead  of  Nos.  1  and  2;  No.  7,  small 
pins  ahead  of  Nos.  5  and  6;  No.  3  follows  Nos.  1,  and  2 
drives  the  guy  pins  home.  No.  7,  after  distributing  his  pins, 
takes  an  axe  and  drives  home  the  pins  behind  Nos.  5  and  6. 
No.  4,  after  distributing  his  pins,  follows  No.  3  and  loops  the 
guy  ropes  over  the  pins. 

Nos.  1,  2  and  3,  the  pins  being  driven,  slip  under  the  tent 
and  place  the  pin  of  the  pole  through  the  tent  and  hood  rings 
while  the  noncommissioned  officer  in  charge  places  the  hood  in 
position.  Nos.  1,  2  and  3  then  raise  the  pole  to  a  vertical  posi- 
tion and  insert  the  end  in  the  socket  of  the  tripod.  They  then 
raise  the  tripod  to  its  proper  height,  keeping  the  center  of  the 
tripod  over  the  center  pin.  While  they  hold  the  pole  vertical 
Nos.  4,  5,  6  and  7  adjust  four  guy  ropes,  one  in  each  quadrant 
of  the  tent,  to  hold  the  pole  in  its  vertical  position,  and  then 
the  remaining  guy  ropes.  As  soon  as  these  are  adjusted  the 
men  inside  drive  a  pin  at  each  foot  of  the  tripod,  if  necessary, 
to  hold  it  in  place. 


To  STRIKE  COMMON,  WALL  AND  CONICAL  WALL  TENTS 

1,  Strike  tent*.     2,  DOWN. 

The  men  first  remove  all  pins  except  those  of  the  four  cor- 
ner guy  ropes — four  quadrant  guy  ropes  in  case  of  the  conical 
wall  tent.  The  pins  are  neatly  piled  or  placed  in  their  recep- 
tacle. 


5-K5  MILITARY  SIGXAL  CORl'S  MAXUAL 

One  man  removes  each  guy  from  its  pin,  and  all  hold  the 
tent  in  a  vertical  position  until  the  command  down,  or  the  last 
note  of  the  general,  and  then  lower  it  to  the  indicated  side. 

The  canvas  is  then  folded,  or  rolled,  and  tied,  the  poles,  or 
tripod  and  pole  fastened  together  and  the  remaining  pins  col- 
lected. 

x 

To  FOLD  TEXTS 

Wall  Tents. — Spread  the  tent  flat  on  its  side  and  place  all 
guys  but  two  over  on  the  canvas  ;  fold  the  triangular  ends  over 
so  as  to  make  the  canvas  rectangular ;  fold  both  ends  so  that  they 
meet  at  the  center,  and  then  fold  one  end  over  on  the  other; 
fold  the  bottom  and  ridge  over  so  that  they  meet  at  the  center 
of  the  strip,  and  then  fold  one  end  over  the  other. 

Fold  the  fly  into  four  folds,  parallel  to  its  length,  then  in  a 
similar  manner  across  its  length,  making  a  rectangle  with 
dimensions  about  the  same  as  the  folded  tent. 

Place  the  fly  on  the  tent,  cross  the  two  free  guys,  and  tie 
them  so  that  they  pass  over  the  ends  and  across  the  sides. 

The  hospital  and  command  tent  are  folded  in  the  same 
manner  as  the  wall  tent. 

Conical  wall  tents. — Spread  the  tent  flat,  with  the  door  up ; 
holding  the  ring  vertical,  fold  the  two  edges  in  so  they  meet  at 
the  center,  and  again  fold  in  the  same  manner ;  place  the  hood 
on  one  half  and  fold  the  other  half  over  on  it;  turn  wall  over 
toward  ring,  fold  coming  at  about  middle  of  height  of  wall; 
two  men  working  together  then  roll  from  the  ring  down, 
placing  knees  on  each  fold  to  make  bundle  compact  and  flat. 

Tie  the  bundle  with  the  two  free  guys,  as  in  case  of  the 
wall  tent. 

GENERAL   REMARKS 

As  soon  as  the  lines  of  company  streets  are  established  the 
positions  of  the  tents  should  be  marked,  from  the  flank  nearest 
the  officers'  tents,  by  pins.  The  front  pole  of  the  wall  and 
common  tent  and  the  door  pins  of  the  conical  wall  tents  occupy 
the  points  so  marked.  The  distance  between  pins  may  be 
determined  by  pacing  or  by  a  light  cord  with  the  distances 
marked  upon  it.  These  distances  are:  For  wall  tents,  8  paces; 
common  tents,  6  paces ;  conical  wall  tents,  10  paces.  The  pins 
marking  the  position,  of  the  tents  are,  when  practicable,  set 
on  a  straight  line,  and  the  company  officers  verify  and  correct 
the  alignment  of  such  pins  in  the  quickest  and  most  convenient 
manner. 


CAMPS  547 

\Yall  pins  are  so  driven  as  to  slope  slightly  away  from  the 
tent;  guy  pins  so  as  to  slope  slightly  toward  the  tent. 

Each  tent,  its  fly,  hood,  poles,  and  tripod,  should  have  the 
same  number. 

The  conical  wall  tent  complete  consists  of  1  tent  and  hood, 
76  pounds;  1  tent  pole  and  tripod,  32  pounds;  48  pins,  about 
20  pounds;  total  weight,  128  pounds.  Its  dimensions  are: 
Diameter,  16^  feet;  height,  10  feet;  height  of  wall,  3  feet; 
packed,  contains  13  cubic  feet. 

The  wall  tent  complete  consists  of  1  tent,  43  pounds  ;  1  fly, 
15  pounds;  1  set  poles,  25  pounds;  10  large  and  18  small  tent 
pins,  about  15  pounds;  total  weight,  98  pounds.  Its  dimensions 
are:  Length  of  ridge,  9  feet;  width,  8  feet  11  inches;  height, 
Bl/2  feet ;  height  of  wall,  3  feet  9  inches ;  packed,  contains  6 
cubic  feet. 

The  common  tent  complete  consists  of  1  tent,  26  pounds;  1 
set  poles,  15  pounds;  24  small  tent  pins,  weight  about  9  pounds; 
total  weight,  50  pounds.  Its  dimensions  are:  Length  of  ridge, 
6  feet  11  inches;  width,  8  feet  4  inches;  height,  6  feet  10  inches; 
height  of  wall,  2  feet. 

The  shelter-tent  equipment  of  each  enlisted  man  consists 
of  the  following: 

(a)  One  shelter  half,  weight  3  pounds. 

(b)  One  pole  in  3  joints,  47  inches  long;  weight,  10^2  ounces. 

(c)  Five  tent  pins.  9  inches  long;  weight,  10  ounces. 

The  shelter  tent  is  pitched  by  two  men,  whose  combined 
equipment  make  a  complete  tent.  The  tent,  when  pitched, 
occupies  a  space  5  feet  4  inches  deep  and  6  feet  4  inches  wide; 
the  two  triangular  parts,  when  pinned  to  the  ground,  inclose 
an  additional  triangular  space  20  inches  deep. 

In  striking  tents,  common  and  wall  tents  are,  unless  other- 
wise directed,  lowered  to  the  right  facing  out  from  the  tent 
door;  conical  wall  tents  away  from  the  door. 

BREAKING    CAMP 

Camp  will  be  broken  in  the  following  order:  Immediately 
after  reveille  the  men  will  feed  their  horses  and,  if  time  per- 
mits, groom  for  20  minutes. 

Tents  \vill  be  struck  and  rolls  made,  which  is  followed  by 
breakfast,  then  water  call,  followed  by  boots  and  saddles.  The 
picket  lines  are  placed  upon  the  transportation  and  the  organi- 
zations formed  as  directed. 


COMPANY  GUARD  MOUNTING 

At  the  assembly  the  men  warned  for  stable  or  other  guard 
duty  fall  in  on  the  company  parade  in  two  ranks,  facing  to 
the  front;  the  senior  non-commissioned  officer  on  the  right  of 
the  front  rank,  the  other  non-commissioned  officers  and  the 
supernumerary  in  the  file  closers. 

The  first  sergeant  verifies  the  detail,  dresses  it  to  the  right, 
and  inspects  the  arms,  equipment,  and  appearance  of  the  men, 
and  replaces  by  the  supernumerary  any  man  unfit  to  march 
on  guard. 

•  He  then  takes  post  4  yards  to  the  front  of  the  detail  facing 
it,  and  commands:  1.  Guard  to  its  post,  2.  Right,  3.  FACE;  4, 
Forward,  5.  MARCH. 

At  the  fifth  command  the  guard  moves  to  its  post;  the 
senior  non-commissioned  officer  marching  near  its  left  and 
rear,  his  place  as  guide  being  taken  by  a  file  closer.  The 
supernumerary  is  then  dismissed. 

When  an  officer  mounts  the  guard  he  will  take  post  6  yards 
in  front  of  the  detail;  the  first  sergeant  will  salute  and  report 
to  him  the  result  of  his  verification  of  the  detail  and  will  then 
face  to  the  left  and  take  post  2  yards  to  the  left  of  the  front 
rank.  The  officer  will  inspect  the  detail  and  march  the  guard 
to  its  post  as  above  described. 

On  arrival  at  the  guardhouse  or  other  designated  place  the 
commander  of  the  old  guard  will  give  the  commander  of  the 
new  guard  all  the  information  and  instructions  relating  to 
his  guard  and  turn  over  to  him  all  property  or  prisoners  in 
his  charge.  The  guard  will  then  be  divided  into  reliefs  and 
the  men  designated  for  the  different  posts,  less  the  com- 
mander of  the  guard,  and  the  members  of  the  first  relief  will 
relieve  the  corresponding  members  of  the  relief  of  the  old 
guard  on  post.  When  all  of  the  members  of  the  old  guard 
have  been  relieved  the  old  guard  will  be  dismissed  by  its 
commander. 

548 


THE  SIGNAL  CORPS  AND  GENERAL  COAST  DEFENSE 

The  United  States,  unlike  other  great  nations  of  the  world,  has 
never  established,  and  may  never  need  to  establish,  permanent  forti- 
fications on  the  land  frontiers,  since  the  real  frontiers  are  the  seas. 
But  even  without  the  obligation  of  defense  against  neighbors  to  the 
north  and  south,  the  vast  extent  of  the  coast  imposes  upon  the 
country  a  duty  which  can  but  grow  greater  as  population  and  wealth 
advance  and  as  the  power  and  number  of  commercial  ships  and  of 
navies  increase.  Types,  speed,  and  size  of  ships  are  bringing  alien 
shores  yearly  into  more  intimate  relations  and  are  making  sea 
attack  more  easy,  more  swift,  and  more  dangerous  than  ever 
before.  The  weight  and  range  of  floating  batteries,  the  number 
and  speed  of  merchant  vessels  and  their  great  transporting  power, 
the  swarms  of  rapid  and  dependable  auxiliaries,  the  submarine,  the 
airplane,  and  the  dirigible,  leave  all  but  strongly  protected  coasts 
without  the  chance  of  defense  in  war,  except  by  airships  and  sub- 
marines and  of  course  the  mobile  army,  and  fixed  defenses  in 
addition  to  a  navy  whose  duty  at  the  outset  may  call  it  into  distant 
seas.  The  probability  of  the  absence  of  the  navy  at  the  very  moment 
when  coast  protection  becomes  most  necessary  is  so  strong  as  to 
amount  to  a  certainty. 

Regarding  the  defense  of  the  seaboard  of  the  United  States,  it 
appears  clear  in  retrospect  that  the  inertia  which  for  years  followed 
the  close  of  the  civil  war  and  the  later  days  of  tranquility  prevented 
the  making  by  the  nation  of  any  serious  effort  to  protect  the  coasts 
of  the  country  from  foreign  attack  until  some  thirty  years  ago  when 
indifference  began  to  give  way  to  the  demand  for  an  efficient 
navy.  The  growth  of  the  navy  in  turn  emphasized  the  need  of  pro- 
tected harbors  and  of  permanent  defenses ;  and  as  the  fortifications 
required  soldiers  to  man  them  attention  was  at  last  directed  more 
and  more  strongly  to  the  personnel  of  the  defense.  At  last  the  coast 
artillery  was  given  a  working,  if  still  a  skeleton,  organization; 
efficient  armament  and  satisfactory  equipment  were  added;  systems 

549 


550  MILITARY  SIGNAL  CORPS  1L  /AT. / L 

of  fire  control  and  direction  were  devised  and  at  least  partial  lines 
of  information  installed.  Finally  it  began  to  be  understood,  though 
dimly  at  first,  that  defenses  themselves  must  be  defended ;  that  the 
eyes  and  the  hands  of  men  must  assist  in  coast  protection  and  that 
two  important  factors  of  the  defense,  namely,  the  coast  patrol  and 
the  mobile  army,  must  form  a  front  for  any  adequate  system 
of  protection. 

For  convenience  in  considering  what  follows,  it  is  assumed  that 
in  war  the  coast  defense,  which  combines  the  military  and  naval 
dispositions  and  operations  necessary  to  resist  attack  on  any  part 
of  the  coast  line,  may  be  divided  into  six  factors,  each  related  to 
the  other  in  operation  and  all  dependent  upon  co-ordination  of 
action  to  bring  out  their  full  value.  These  are,  first,  the  fixed 
and  floating  defenses  of  the  artillery,  consisting  of  the  arma- 
ments, submarine  defenses  and  materials,  coast  and  scout  ships,  and 
to  some  extent  air  craft,  torpedo,  submarine,  patrol,  and  picket 
boats ;  the  personnel,  including  all  troops  assigned  to  duty  in  con- 
nection with  the  fixed  defenses.  Second,  the  general  defense  troops 
of  the  regular  or  volunteer  army,  or  of  the  organized  militia,  not 
including  the  supports  of  fixed  positions.  Third,  the  air  service, 
including  the  necessary  aero  squadrons  of  various  types,  with  their 
auxiliary  tractors  and  the  dirigible  when  used  for  coast  patrol  and 
defense.  Fourth,  the  coast  patrol,  including  the  coast  guard. 
Fifth,  the  service  of  the  lines  of  information ;  that  is,  the  Signal 
Corps  of  the  army.  Sixth,  the  navy. 

Although  each  of  these  factors  supplements  the  others,  it  is 
evident  that  the  one  which  binds  them  all  into  a  working  whole, 
and  without  which  the  other  five  will  have  rather  less  cohesion  and 
connection  than  so  many  reeds  shaken  by  the  wind  is  the  Signal 
Corps  in  control  of  the  lines  of  information  and  the  service  of  air 
craft. 

To  arrive  at  a  proper  understanding  of  the  extent  and  charac- 
ter of  the  lines  of  information  necessary  to  keep  in  brain  touch 
the  elements  of  the  defense  of  a  great  seaboard  like  our  own,  it  will 
be  well  to  first  outline  the  general  scope  of  the  defense  and  to 
indicate  the  part  played  by  the  other  factors  in  war. 

The  first  of  the  factors  of  defense  to  be  considered  is  that  of 
the  fortified  positions. 

FORTIFIED  POSITIONS 

PERMANENT  COAST   OR    HARBOR   DEFENSES 

In  general  terms,  the  permanent  defense  of  a  coast  or  harbor 
consists  in  the  adequate  protection  of  a  number  of  distinct  posi- 
tions, which  from  their  importance  to  the  country  or  value  to  the 
enemy  must  be  guarded  against  injury,  occupation,  or  capture 


i;/i.V/:A'.-//.  COAST  DEFENSE  551 

Such  positions  are  either  actually  or  potentially  guarded  perma- 
nently by  a  number  of  fixed  artillery  emplacements,  the  fighting  or 
tactical  units  of  which  constitute  a  chain  of  command.  The  artil- 
lery defense  as  a  whole  is  made  up  of  a  series  of  tactical  areas,  each 
measurably  complete  and  independent  in  itself,  but  separated  usually 
by  considerable  distances  of  coast  from  the  others,  and  the  whole 
kept  in  touch  by  lines  of  information,  usually  commercial,  which 
form  a  chain  encircling  the  country. 

On  the  coasts  of  the  United  States  there  are  eighty-one  separate 
forts  where  modern  defenses  are  installed  or  are  in  process  of 
installation ;  in  the  Philippines  there  are  six ;  in  Hawaii,  four ; 
in  the  Canal  Zone,  five;  a  total  of  ninety-six.  It  is  evident,  there- 
fore, that  the  fixed  defenses  alone  required  a  vast  number  of  lines 
of  information  and,  further,  that  for  the  purpose  of  control  of  its 
vast  coast  line  these  positions  must  be  kept  in  communication  not 
only  with  great  centers  of  population  and  with  the  capital  of  the 
country  but  with  each  other,  and  that  under  certain  probable  condi- 
tions of  war  the  chain  of  defense  from  Portland  to  Galveston,  from 
San  Diego  to  Puget  Sound,  or  perhaps  from  Quoddy  Head  to  the 
Straits  of  Fuca,  must  be  kept  in  constant  and  immediate  touch  by 
telegraph,  telephone,  or  radio.  This,  of  course,  is  largely  a  problem 
for  the  existing  commercial  lines  to  solve. 


It  is  probably  evident  to  all  who  have  considered  the  matter 
that  the  most  necessary  factor  of  the  land  defense  of  the  coast  is 
the  mobile  army,  together  with  its  auxiliaries.  Even  to  the  unthink- 
ing it  must  be  obvious  that  without  such  forces  there  can  be  no 
real  and  substantial  protection  for  the  coasts,  except  at  those  posi- 
tions which  have  been  selected  beforehand  for  fortification,  which 
of  necessity  will  be  few  in  number.  Even  if  these  fixed  defenses 
could  stand  alone,  which  they  can  not  do,  they  will  of  necessity 
form  but  a  partial  and  interrupted  protection  to  an  extended  sea- 
board and  will  leave  open  to  attack  many  important  towns,  service- 
able harbors,  and  landing  places  that  may  be  used  by  an  enemy  as  a 
base  or  as  coaling  and  supply  stations.  The  fortified  positions  are 
really  harbor  defenses  only.  It  is  clear  also  that  a  country  with 
some  5,700  miles  of  coast  line  offered  to  attack,  indented  with 
innumerable  minor  harbors  and  anchorages  and  dotted  with  import- 
ant towns  that  invite  destruction,  can  not  protect  all  its  vulnerable 
points  by  costly  and  extensive  armaments ;  as  a  consequence,  minor 
positions  must  be  otherwise  defended  or  left  to  shift  for  themselves. 
While  the  defending  navy  remains  within  reasonable  distance  of  the 
coast  the  minor  positions  will  be  free  from  danger,  but  a  navy,  if 
efficient,  will  not  remain  at  home.  In  a  serious  war.  therefore,  pro- 


552  MILITARY  SIGNAL  CORPS  MANUAL 

tection  for  the  less  important  positions  must  fall  to  the  care  of  such 
of  the  floating  defenses  as  may  be  withheld  from  distant  seas;  to 
the  troops  of  the  mobile  army,  aided  by  such  land  batteries  as  can 
be  hastily  constructed  and  armed;  to  the  submarine  and  to  the  air 
craft.  Such  partial  defenses  may  not  prevent  attack  and  local 
injury,  but  they  can,  at  least,  prevent  destruction  and  an  occupation 
that  may  provide  the  enemy  with  a  naval  base  and  perhaps  threaten 
invasion  of  the  country  at  large.  Protection  against  this  danger 
rests  with  the  mobile  army  alone,  once  a  foothold  has  been  estab- 
lished on  our  coast. 

The  need  of  a  mobile  army  in  coast  defense  is  not,  however, 
confined  to  the  protection  of  the  lesser  positions  and  harbors  unpro- 
vided with  effective  fortifications  and  armament,  for  it  is  to  be 
remembered  that  coast  fortifications  of  today,  unlike  the  permanent 
works  of  an  earlier  time,  look  only  toward  the  sea,  and  of  them- 
selves are  helpless  against  land  attack ;  hence  they  must  be  pro- 
tected at  flank  and  rear  from  approach  by  hostile  troops  and  landing 
parties. 

In  these  days  every  serious  sea  attack,  to  be  successful,  must  be 
accompanied  by  land  operations,  a  fact  well  illustrated  by  the  fall 
of  Tsingtau  and  especially  by  the  desperate  sea  fights  of  the  Darda- 
nelles and  of  the  Gallipoli  Peninsula  and  the  subsequent  land  attacks. 
It  is  evident  that  though  ships  unsupported  may  cause  great 
damage  and  even  destroy  cities  or  fortified  positions,  they  can 
produce  but  little  effect  upon  the  ultimate  result  of  a  campaign 
unless  combined  with  land  operations,  by  means  of  which  the 
defense  is  not  only  destroyed,  but  overwhelmed,  the  objective  occu- 
pied, together  with  the  surrounding  regions. 

It  appears,  then,  that  the  country  must  be  .prepared  to  prevent 
throughout  the  vast  extent  of  its  seaboard  the  seizure  and  occupa- 
tion of  any  one  of  many  important  points,  both  fortified  and 
unfortified,  and  of  all  of  its  harbors  and  landing  places  useful  to  an 
enemy.  This  implies  the  existence  of  a  mobile  force  so  placed  and 
so  large  and  effective  in  organization  as  to  insure,  on  the  one  hand, 
the  safety  of  exposed  positions  by  proper  dispositions  of  troops 
immediately  needed ;  and,  on  the  other,  by  concentration  of  the 
major  part  of  these  mobile  troops  in  reserve  at  strategic  positions 
of  the  coast  or  possibly  of  the  other  frontiers  as  to  permit  the  use 
of  an  overwhelming  number  of  defense  troops  at  any  threatened 
point. 

In  the  defense  by  a  mobile  army  the  plan  adopted  may  well  be 
somewhat  as  follows:  The  Atlantic,  the  Gulf,  and  the  Pacific  sea- 
boards will  be  divided  into  defensive  areas,  the  extent  and 
boundaries  of  which  will  depend  upon  strategic,  geographical,  and 
economic  conditions.  These  areas  will  not,  as  a  rule,  be  coextensive 
with  military  departments,  since  they  depend  upon  different  condi- 


GENERAL  COAST  DEFENSE         553 

tions  and  lie  mainly  along  the  sea.  They  will  be  controlled  by  their 
own  general  officers,  acting  presumably  under  one  chief.  In  each 
area  there  will  exist  in  war  a  mobile  force  adequate  not  only  for 
its  defense  proper — that  is,  for  land  defense  of  fixed  positions, 
unprotected  harbors,  and  other  vulnerable  points  within  the  area 
itself — but  for  service  with  other  troops  mobilized  and  held  as  a 
general  reserve.  Within  defensive  areas  there  will  be  placed  a 
sufficient  number  of  men  of  the  regular  army,  of  the  trained  citi- 
zenry, and  of  the  organized  militia  of  the  state  or  neighboring 
states  to  form  a  nucleus  of  the  force  required.  In  addition  to  the 
aero  squadrons,  which  form  part  of  a  division  of  the  mobile  army, 
there  should,  of  course,  be  gathered  together  all  of  the  flying  men 
who  can  be  brought  into  service  with  the  militia  or  the  volunteers, 
and  to  them  should  be  allotted  the  duty  of  watching  the  coasts,  so 
far  as  practicable. 

It  should  be  evident  that  of  this  force  the  men  most  needed 
in  the  preliminary  work  of  the  defense  are  not  coast  artillerymen 
alone,  but  engineers,  and  signal  troops,  especially  of  the  aviation 
section,  since  the  first  step  in  mobilization  is  the  establishment  of 
lines  of  information,  of  which  soldiers  alone  should  be  in  control, 
and  the  training  of  airmen. 

The  mobile  troops  of  the  coast  defense  obviously  require  ample 
strength  in  engineer  and  signal  troops,  field  and  horse  artillery,  and 
a  due  proportion  of  cavalry  to  erect  and  defend  the  field  works  on 
the  land  fronts  of  fixed  positions,  to  establish  and  maintain  lines 
of  information,  to  check  sudden  attempts  at  coast  landing,  and  to 
perform  the  duties  of  mounted  troops  in  the  field  and  for  air  ser- 
vice. 

It  is  certain  that  if  so  trained  the  small  quotas  of  state  troops, 
are  of  the  utmost  value  to  the  defense  at  a  time  when  the  lines  of 
information — the  telegraph,  the  telephone,  radio  and  air  service — 
are  urgently  needed  in  the  organization,  disposition,  and  control  of 
newly  organized  levies.  Together  with  the  signalmen  of  the  regular 
army,  they  may  well  undertake  the  organization  of  additional  signal 
troops  from  the  citizenry  called  to  the  colors. 

If  it  becomes  necessary  to  put  forth  the  strength  of  the  country 
by  calling  to  the  colors  the  larger  part  of  the  mighty  reserve  avail- 
able for  national  defense,  it  is  certain  that  the  total  number  of 
men  of  the  ultimate  levy  will  be  so  enormous  that  occasion  for 
mobilizaton  of  the  whole  can  hardly  arise.  But  though  the  leve  en 
masse  may  never  be  resorted  to  in  this  country,  a  force  called  to 
the  national  defense  in  a  great  war  is  no  small  thing,  and  the  work 
of  turning  it  into  an  efficient  army  and  of  supplying  it  with  an 
adequate  force  of  technical  troops  properly  equipped  for  the  field 
requires  the  best  efforts  of  every  trained  man  of  the  service. 


554  MILITARY  SIGNAL  CORPS  MANL'AL 

General  levies  are  certain  at  first  to  be  weak  in  these  very  arms, 
since  they  are  of  necessity  almost  nonexistent  with  the  organized 
militia  of  many  of  the  states  in  ordinary  times.  Lack  of  the  assist- 
ance of  technical  troops  hampers  the  defense,  gives  to  the  troops 
little  mobility,  and  compels  them  to  remain  tied  to  their  base  or 
semi-permanent  camps.  This  condition  will  doubtless  be  corrected 
as  time  goes  on,  but  its  existence  at  first  multiplies  the  lines  of 
information  and  the  duties  of  signal  troops.  It  is  certain  therefore 
that  the  communications  by  which  the  first  line  and  the  reserves 
will  be  linked  together  and  to  the  permanent  works  should  from  the 
early  efforts  at  concentration  be  ample  and  effective,  and  so  continue, 
for  without  them  the  whole  army  of  the  defense  becomes  a  mere 
aggregation  of  inert  units. 

SUPPORTS 

A  third  class  of  troops  organized  are,  if  not  large  in  number,  at 
least  of  vital  importance  in  coast  defense ;  they  are  the  supports 
of  artillery  positions  proper.  These  men,  placed  at  stations  suitable 
to  the  defense  of  fixed  positions  against  land  attack,  act  in  concert 
with  the  coast  artillery  and  are  under  the  immediate  command  of 
artillery  officers,  presumably  of  posts  or  districts,  since  it  is  evident 
that  they  must  be  kept  as  directly  in  touch  with  the  officers  fighting 
the  positions  as  are  the  marines  aboard  ship.  The  supports  may  well 
be  drawn  from  the  mobile  troops  proper  and  be  composed  of  the 
first  and  best  men  called  to  the  general  defense ;  that  is,  of  such 
troops  of  the  regular  army  as  can  be  assigned  to  the  duty  and  of 
the  flower  of  the  organized  militia.  Made  up  almost  entirely  of 
infantry  and  field  artillery,  with  as  many  machine-gun  batteries  as 
may  be  available,  there  should  be  added  a  far  larger  proportion  of 
signalmen  than  is  usually  considered  necessary  for  an  army  in  the 
field,  since  upon  these  men  falls  the  service  of  information  not 
merely  with  other  elements  of  artillery  defense,  but  with  the  fixed 
positions,  the  mobile  troops,  coast  guard,  and  with  the  navy. 

The  lines  of  information  of  these  supporting  troops  are  those 
of  the  field  army.  They  will  be  mainly  dependent  upon  the  buzzer, 
airplane — or  perhaps  the  dirigible — the  radio,  field  telegraph  or 
telephone,  and  visual  signaling. 

In  considering  defense  against  invasion,  it  should  appear  that 
the  mobile  troops  indicated  will  stretch  over  many  miles  of  coun- 
try and  operate  under  widely  varying  conditions.  Even  more  than 
for  a  well-organized  army  in  campaign,  therefore,  the  lines  of 
information  for  the,  at  first,  somewhat  unorganized  forces  of  the 
general  defense  must  be  ample  and  widely  extended. 

Indeed,  except  in  emergencies,  these  lines  are  more  necessary  in 
the  early  days  of  the  defense  than  later  when  the  machine  moves 


GENERAL  COAST  DEFENSE  555 

smoothly,  but  at  all  times  the  mobile  troops,  without  an  adequate 
service  of  information,  have  rather  less  direction  and  mobility  than 
a  collection  of  tortoises.  Properly  laid,  the  lines  of  information 
not  only  form  a  network  throughout  the  defense  area  but  tie  each 
theater  of  operations  to  the  others  and  provide  the  entire  army 
with  the  lines  heretofore  shown  to  be  essential  in  the  field. 

With  headquarters  of  the  defense  and  those  of  mobile  troops 
fixed  at  the  places  best  suited  tactically  for  the  purpose — and  it  is 
reasonably  certain  that  these  positions  lie  at  centers  of  commercial 
activity — they  will  be  distant  from  the  camps  of  divisions  and 
brigades  and  still  farther  separated  from  the  smaller  commands 
and  detachments,  from  the  artillery  headquarters  and  from  obser- 
vation stations  and  outposts  of  coast  defense.  Yet  with  all  these 
commanding  officers  of  the  mobile  forces  must  be  kept  in  constant 
and  immediate  touch,  as  well  as  with  the  military  commanders 
of  departments,  should  the  latter  not  be  in  command  of  the 
general  defense — and  with  Washington.  In  turn,  army,  division, 
and  brigade  headquarters  must  be  kept  in  communication  with 
dependent  and  outlying  commands ;  these  with  the  observation  sta- 
tions and  coast  patrol ;  and  the  latter  given  the  power  to  com- 
municate readily  with  the  floating  defenses,  with  artillery  districts, 
and  with  ships. 

For  the  mobile  coast  army  the  systems  of  information  needed 
are  even  more  extensive  and  varied  than  is  considered  necessary 
for  a  field  army  in  campaign;  and  it  follows  that  the  proportion 
of  signal  troops  to  line  soldiers  in  coast  defense  should  be  in- 
creased. 

It  is  hopeless  to  suppose  that  the  Signal  Corps  of  the  regular 
establishment  can  ever  supply  more  than  a  leaven  for  the  mass  of 
men  needed,  especially  for  the  air  service,  or  even  that  the  militia 
possessing  signal  troops  of  approved  efficiency  can  provide  more 
than  the  framework  of  the  organizations  required.  The  signal 
troops  mobilized  for  war  must  be  filled  in  by  men  drawn  direct 
from  civil  life.  But  excellent  and  abundant  as  the  material  for 
these  troops  undoubtedly  is  among  the  men  engaged  in  the  elec- 
trical and  mechanical  pursuits  of  the  country,  and  from  the  few 
who  have  been  trained  in  airplane  work,  such  men  before  they 
can  be  of  any  real  value  must  be  made  into  soldiers.  The  Signal 
Corps  of  the  army  will  never  have  the  numbers  or  the  opportunity 
to  take  upon  itself  alone  this  training  and  the  assistance  of  the 
organized  militia  and  of  suitable  and  willing  men  in  civil  life  must 
be  asked  and  given.  The  training  must  be  quick  and  effective, 
and  therefore  be  performed  by  men  who  have  themselves  been 
drilled  in  peace  in  the  methods  of  the  Signal  Corps  of  the  army. 
Unfortunately,  trained  militiamen  and  airmen  are  at  present  few 


556  MILITARY  SIGNAL  CORPS  MANUAL 

Itnd  are  confined  to  a  small  number  of  states,  and  even  where  signal 
organizations  exist,  they  are  not  always  given,  be  it  said  without 
disparagement  of  the  troops  themselves,  the  strength  in  numbers. 
the  equipment,  nor,  up  to  now,  the  training  to  make  them  imme- 
diately valuable  in  coast  defense. 

SERVICE  OF  AIRCRAFT  IN  COAST  DEFENSE 

A  third  and  very  important  factor  in  coast  defense  is  the  serv- 
ice of  air  craft,  and  it  is  becoming  increasingly  evident  that  in 
addition  to  lines  of  information  laid  or  worked  on  land,  there 
must  now  be  recognized  and  carefully  considered  the  part  played 
in  coast  defense  and  observation  by  aerial  fleets.  It  is  not  in- 
tended here  to  speak  of  the  airplane  merely,  but  to  suggest  also  the 
potential  value  of  the  lighter-than-air  craft,  whose  special  use  is 
now  thought  to  be  in  scouting  or  reconnaissance  work,  which 
means,  of  course,  its  use  as  a  coast  patrol. 

Divided  into  areas  or  districts  patrolled  by  dirigibles  or  air- 
planes, all  communicating  back  to  central  stations  and  maneuvering 
far  out  to  sea,  such  scouts  should  make  impossible  a  hidden  ap- 
proach or  surprise  attack  by  an  enemy.  The  captive  balloon  also 
finds  a  useful  place  in  service  of  this  kind.  But  the  time  has  not 
yet  arrived  to  indicate  definitely  what  form  the  defense  air 
service  will  take.  It  has  been  suggested  that  the  coasts  of  the 
country  be  divided  into  sections  or  areas,  each  of  which  should 
contain  an  aerodrome  or  center  from  which  scouting  land  and 
sea  planes  could  operate  at  sea  and  send  reports  by  radio,  if 
satisfactorily  installed,  to  the  central  stations  regarding  the  move- 
ments of  enemies'  or  friendly  ships. 

Whether  this  air  patrol  shall  eventually  be  installed  and  con- 
ducted by  the  army,  the  navy,  or  the  coast  guard  is  undecided, 
and  in  the  present  condition  of  affairs  is  not  a  matter  requiring 
consideration  here.  There  is  involved,  however,  a  vast  and  im- 
portant field  of  Signal  Corps  work,  not  alone  in  this  aviation  service, 
but  in  the  transmission  by  wire,  radio  or  otherwise,  news  received 
from  aircraft  at  central  stations,  often  located  at  isolated  points, 
to  the  proper  headquarters. 

The  fourth  factor  of  the  coast  defense,  and  that  one  which 
depends  for  its  value,  if  possible,  even  more  closely  upon  the 
lines  of  information  than  others,  is  the  coast  patrol,  or  coast  guard, 
as  it  is  now  called. 

THE  SIGNAL  CORPS  AND  THE  COAST  GUARD 

To  a  student  of  the  present  condition  of  our  defense  it  will 
perhaps  appear  that  the  important  subject  of  coast  observations. 
or  coast  patrol,  has  not  received  from  the  army  the  attention  it 


GENERAL  COAST  DEFENSE  557 

deserves.  Radio  and  signal  stations  have  been  erected  within 
artillery  districts,  and  by  the  navy;  but  great  stretches  of  coast, 
often  containing  good  harbors,  landing  beaches  and  magnificent 
lookout  stations  remain  without  the  means  of  rapidly  communi- 
cating their  news  to  the  telegraph  and  telephone  lines  of  the 
country.  At  many  of  the  lookout  stations  valuable  information 
of  friend  or  enemy  at  sea  may  be  gathered,  yet  they  remain  in 
general  unprepared  for  service  in  war.  The  need  of  the  co- 
operation of  the  trained  men  and  efficient  equipment  prepared  by 
the  Signal  Corps  for  just  this  kind  of  work  is  important. 

Without  the  full  co-operation  of  the  Signal  Corps  of  the  army 
and  the  participation  of  troops  trained  in  the  service  of  lines  of 
information  and  in  the  use  of  the  airplane ;  the  establishment  of 
signal  stations,  and  telegraph,  telephone,  and  buzzer  lines ;  cables ; 
the  captive  balloon  and  the  dirigible,  it  is  hard  to  see  not  merely 
how  the  best  methods  of  gathering  intelligence  in  war  can  be 
employed  by  a  coast  guard,  but  how,  when  so  gathered,  the  infor- 
mation obtained  can  be  transmitted  to  the  centers  of  control,  to 
artillery  fixed  positions  and  their  auxiliaries,  and  to  the  mobile 
army  from  distant  observation  stations,  coast  islands,  and  light- 
houses, or  from  the  floating  auxiliaries  and  passing  ships,  with 
the  speed  and  certainty  which  alone  make  such  information 
valuable. 


COAST    DEFENSE    INFORMATION    IN    WAR 

In  general  it  appears  evident  that  the  service  of  security  and 
information  in  coast  defense,  as  in  the  field,  implies,  first,  the 
collection  of  military  information  or  intelligence  j  second,  its 
transmission ;  and,  third,  its  correlation  and  use.  In  regard  to  the 
first  of  these  elements  it  may  be  said  that  the  collection  of  infor- 
mation, is  primarily  the  duty  of  the  coast  patrol,  but  in  war  becomes 
the  duty  of  the  mobile  army,  the  fixed  defenses,  and  of  every  man 
of  the  government  service,  both  civil  and  military,  and,  indeed,  of 
all  people  of  the  country.  But  although  important  information 
may  thus  come  from  many  sources  and,  no  matter  what  the  source, 
should  be  transmitted  to  proper  authority,  yet  incidental  informa- 
tion, like  incidental  soldiering,  is  merely  auxiliary  to  the  organized 
service  of  information.  The  continued  value  of  this  service 
depends  upon  a  properly  organized  corps  of  men  who  will  transmit 
the  reports  of  trained  observers  from  the  aircraft,  signa/,  and 
observation  stations,  from  lighthouses  and  other  government  es- 
tablishments, from  the  floating  auxiliaries  and  ships  as  well  as 
from  chance  sources  of  information,  and  from  the  thousand  watch- 
ers of  the  coast,  upon  all  of  whom  reliance  must  be  placed  in  war 
to  collect  that  information  upon  which  will  depend  the  attitude  of 
the  defense. 

But  both  judgment  and  experience  in  regard  to  the  weight  to  be 
given  this  information  will  be  needed  by  officers  and  men  in 
charge  of  this  service,  and  of  its  transmission,  if  a  constant  con- 
dition of  unrest  and  excitement  is  to  be  avoided  at  inshore  termi- 
nals. Who  can  doubt,  for  example,  that  information  received  at 
the  centers  of  control  will  determine  the  attitude  of  the  army 
of  the  defense  in  threatened  areas,  and  perhaps  its  ability  to  prevent 
surprise  or  repel  attack;  that  the  news  or  no  news,  often  equally 
important,  from  the  coast  will  govern  the  preparedness  and  vigi- 
lance of  the  mobile  troops  and  supports  and  keep  the  artillerymen 
at  the  guns  or  give  them  release ;  that,  in  short,  a  well-organized 
service  provided  with  trained  men  skilled  in  the  use  and  main- 
tenance of  lines  of  information  will  relieve  the  defense  of  the 
greater  part  of  its  strain  in  the  absence  of  the  enemy,  multiply 

558 


INFORMATION  IN  WAR  559 

many  times  its  efficiency  in  his  presence,  and  permit  the  smaller 
force  to  do  the  work  of  the  larger.  While,  on  the  other  hand,  an 
insufficient  service  of  information,  handicaped  by  slow,  inaccurate, 
or  faulty  transmission,  will  plague  and  worry  the  defense  with 
useless  anxieties  and  alarms,  if  it  does  not  even  lead  on  to 
disaster. 

The  transmission  of  information,  which  is  the  second  element 
of  the  service  of  security,  is  a  duty  of  vital  importance,  which 
should  be  intrusted  only  to  trained  men  under  military  control, 
supplied  with  the  best  known  appliances  for  this  service,  and 
should  never  be  left  to  the  chance  efforts  of  any  irresponsible  per- 
son who  can  use  a  telegraph  key  or  a  radio  instrument.  In  other 
words,  that  the  section  of  the  coast  guard  to  which  the  duty  of 
transmission  of  information  is  intrusted  should  be  composed  of 
men  trained  in  naval  and  military  signaling  and  familiar  with  the 
methods  of  the  Signal  Corps  of  the  army. 

With  the  use  that  will  be  made  of  the  information  when 
received,  which  is  the  third  element  of  the  service  of  security,  the 
patrol  has  no  concern,  since  this  will  depend  upon  commanding 
generals,  and  the  reception  and  correlation  of  reports  upon  staff 
officers  at  headquarters,  presumably  signal  officers,  whose  duty  it 
should  be  to  formulate  and  weigh  the  information  transmitted. 

It  appears  that  the  coast  patrol  will  become  in  the  future  one 
of  the  strongest  arms  of  that  service  of  security  and  information 
upon  which  so  much  dependence  is  necessarily  placed  in  modern 
war.  It  follows,  and  it  cannot  be  doubted,  that  this  patrol  or 
guard  when  organized  should  be  thoroughly  efficient  in  numbers, 
personnel,  organization,  and  equipment,  and  that  its  men,  who  are 
frequently  placed  at  lonely  stations  and  required  to  act  upon 
their  own  initiative,  should  be  not  only  steady,  well-disciplined 
soldiers,  but  in  addition  must  be  carefully  selected,  intelligent, 
and  keen  men,  skilled  as  observers  and  trained  in  the  use  of  the 
telegraph  and  of  mechanical  appliances.  Besides  all  this  they 
should  possess  that  judgment  which  seldom  blunders  in  its  work. 
Fortunately  for  the  country,  men  of  this  character  are  many  in 
civil  life  and  will  be  found  in  abundance  when  called,  but  these 
men  must  be  trained  as  soldiers. 

The  work  of  installing  the  fire  control  was  formerly  performed 
by  the  Signal  Corps  of  the  army,  and  many  of  the  types  of  instru- 
ments used  have  been  designed  or  adapted  by  the  corps.  But  in 
addition  to  the  fire-control  systems  there  must  exist  both  within 
and  without  artillery  districts  the  fifth  factor  of  the  coast  defense, 
that  is  lines  of  information,  whether  electrical  or  visual,  by  means 
of  which  artillery  headquarters  are  kept  in  touch  with  the  interior 
of  the  country  and  with  centers  of  control;  the  factors  and  ele- 
ments of  the  defense  are  brought  into  co-ordination :  fixed  positions 


560  MILITARY  SIGNAL  CORPS  MANUAL 

connected ;  and  the  district  bound  into  a  whole  under  control  of 
its  commander,  as  an  army  in  the  field  is  linked  together  and 
maneuvered  by  »'i  general. 

These  units  are,  as  a  rule,  separated  from  each  other  by  con- 
siderable distances.  Each  headquarters,  however,  is  kept  in  touch 
with  the  others  electrically,  mainly  through  the  commercial  sys- 
tems of  the  country;  but  the  commercial  systems  are,  of  necessity, 
frequently  supplemented  by  military  lines,  which  extend  them  to 


ILLUSTRATING    TWO    VISUAL    AND    ONE    ELECTRICAL    MEANS    OF 

SIGNALING;  HELIOGRAPH  AND  WIGWAG  AT  LEFT, 

WIRELESS  ON   RIGHT 


artillery  headquarters.  Within  artillery  areas  the  various  posts 
may,  or  may  not,  be  reached  by  commercial  systems ;  even  district 
headquarters,  when  placed  on  coast  islands  or  at  other  isolated 
and  scantily  peopled  localities,  from  which  the  money  returns  would 
be  small  and  the  expense  of  installation  and  maintenance  of  land 
lines  and  cables  would  be  great,  are  dependent  at  all  times  upon 


INFORMATION  IN  WAR  561 

military  lines  of  infortration  for  communication  with  the  outer 
world  as  well  as  with  the  fixed  positons  themselves. 

In  general,  artillery  lines  of  fire  control  and  of  information 
(except  the  field  lines  necessary  in  maneuvers)  are,  in  peace, 
permanent  in  type;  but  in  war  to  permanent  lines  are  added  a 
network  of  temporary  systems  as  flexible  and  extensive  as  need 
be,  and  in  character  resembling  those  of  an  army  in  campaign. 
These  may  be  more  limited  in  extent,  perhaps,  but  based  on  more 
stable  conditions  they  are  consequently  easier  to  install  and  main- 
tain against  interruption  by  an  enemy,  except  in  the  case  of  the 
radio.  If  interrupted,  repairs  are  easier  made,  since  the  material 
should  always  be  at  hand  at  the  fixed  positions,  But  as  with  lines 
of  information  in  the  field,  those  of  the  coast  defense,  both  per- 
manent and  temporary,  must  be  certain  and  speedy.  They  will  be 
more  complicated  and  varied  than  is  possible  with  the  former, 
since  they  imply,  in  addition  to  land  lines,  systems  of  information 
extending  both  under  and  over  the  sea,  and  include  in  their  scope 
every  known  method  of  transmitting  intelligence  from  the  wink  of 
the  ardois,  the  flash  of  the  searchlight,  the  tick  of  the  telegraph 
key,  or  call  of  the  buzzer  to  the  message  of  the  long-distance  radio 
and  of  the  airplane  or  dirigible. 

With  the  permanently  laid  lines  of  the  coast  defense  trans- 
mission should,  of  course,  be  as  efficient  and  satisfactory  as  in 
civil  life  if  the  systems  are  properly  installed  and  skillfully  oper- 
ated in  practice ;  but  in  order  to  secure  these  results  it  is  evident 
that  the  ponderous  permanent  systems  of  the  fixed  defenses,  both 
fire  control  and  information,  cannot  be  thrown  out  in  an  hour  like 
the  wires  of  a  marching  army,  but  must  be  carefully  planned  and 
constructed  in  advance  as  the  defenses  themselves  are  planned, 
must  progress  to  completion  with  them,  and  when  in  place  must 
be  proof  against  reasonable  probability  of  interruption. 

Temporary  lines  will,  of  course,  be  installed  only  when 
demanded  by  the  exercises  and  maneuvers  or  by  the  exigencies  of 
war.  Neverthel  ss,  the  means  of  providing  them  should  be  at  hand 
within  each  artillery  district,  so  that  when  needed  field  telegraph 
and  buzzer  lines  may  be  laid  easily,  quickly,  and  without  confusion 
from  district  headquarters  to  the  supports,  mobile  troops,  to  head- 
quarters and  observation  stations  of  the  coast  patrol.  The  tele- 
graph and  telephone,  radio  sets  and  visual  appliances  should  be  in 
readiness  for  use  in  the  exchange  of  signals  between  the  fixed 
positions  and  coast-defense  ships,  patrols,  picket  boats,  and  scout 
ships,  as  well  as  torpedo  planters  r\nd  the  cable  ship  when  neces- 
sary, and  with  the  navy.  The  field  telephone  should  be  ready 
to  tell  its  story  from  observation  stations  and  the  airplane  and 
dirigible  should  be  at  hand  to  send  by  radio  or  visual  signals 
their  messages  from  land  or  sea.  Thus  the  temporary  lines  of 


562 

artillery  districts  will  include  many  aerial  systems,  and  even  the 
permanent  comunications  will  not  be  electrical  alone.  Both  will 
depend  largely  upon  the  auxiliary,  but  still  very  important,  class 
of  visual  and  oral  signals,  which  before  the  introduction  of  the 
radio  telegraph  were  the  only  means  known  of  exchanging  ideas 
without  material  connection.  Visual  signaling  is  probably  more 
important  in  coast  defense  than  with  the  army  in  the  field  and 
is  vital  when  communication  is  needed  between  ships  and  shore 
and  the  radio  is  silent.  Whether  all  the  signal  apparatus  out- 
lined will  be  used  by  the  defense  is  another  matter ;  still  the 
possibility  exists,  and  the  fact  remains  that  opportunity  should 
be  given  those  who  have  control  to  employ  every  method  of 
transmitting  information  that  may  prove  reasonably  valuable.  To 
do  this  it  is  necessary  that  signal  appliances  of  all  useful  kinds 
be  stored  in  depots  within  artillery  areas,  in  addition  to  the  ma- 
terial required  for  the  emergency  repair  of  permanent  systems. 

In  war  the  headquarters  of  each  artillery  position,  even  more 
than  coast  patrol  stations,  becomes  a  nucleus  of  intelligence  re- 
garding events  at  sea,  and  therefore  the  service  of  information  in 
and  from  these  districts  should  be  as  perfect  as  it  can  be  made. 


INDEX 


B 

Bugle    Calls    .  32,  44 

First  Call 33 

Guard  Mounting       ....  33 

Full  Dress 33 

Overcoats      .  33 

Drill 33 

Stable 33 

Water 34 

Boots  and  Saddles         ...  34 

Assembly 34 

Adjutants'    Call        .       .      .      .34 

To  the  Standard      ....  34 

Fire 34 

To  Arms 34 

To  Horse 35 

Reveille 35 

Retreat 35 

Tattoo 36 

Call   to  Quarters      ....  37 

Taps 37 

Mess 37 

Church 38 

Recall 38 

Issue 38 

Officers'  Call 38 

Captain's  Call 38 

First  Sergeant's       ....  38 

Fatigue 38 

Sick 38 

School 39 

The  General 39 

Attention 39 

Mount 39 

Dismount 39 

Form  Rank 39 

Forward  March         ....  39 

Halt 40 

Walk 40 

Trot          40 

Gallop 40 

Guide    Right 40 

Guide  Left 40 

Guide  Center 40 

By  the  Right  Flank      ...  40 

By  the  Left  Flank  ....  40 

Right    About 40 

Left  About 40 

Column  Right 40 

Column   Left 40 

Platoons 41 

Right  Turn 41 


Bugle  Calls   (Continued) 

Left   Turn     .... 

Right    Oblique    .       .      . 

Left   Oblique 

Right    Front   Into   Line 

Left  Front  Into  Line    . 

On  Right  Into   Line      . 

On  Left  Into  Line  . 

Commence    Firing    . 

Cease   Firing 

Route   Order 

President's  March   . 

General's  March 

Flourishes  for  Review  . 

Rogue's  March   . 

Funeral  March   . 

Quickstep    No.    1 

Quickstep    No.    2 

Quickstep    No.    3 

Quickstep    No.    4 

Quickstep   No.    5 

Quickstep    No.   6 
Buzzer,    The    Service 


Calibrating    Wave    Lengths    by 
Wave    Meter 


41 
41 
41 
41 
41 
41 
41 
41 
41 
41 
42 
•42 
42 
42 
43 
43 
44 
44 
44 
44 
44 
290 


387 
287 


Camp  Telephone,  The 
Camps: 

Semi-permanent        ....  531 

Shelter    Tent 532 

Selection  of  Sites     ....  534 

Field     Battalion        ....  535 

Telegraph    Battalion      ...  539 

Water    Supply 540 

Kitchen 541 

Disposal    of   Excreta      .       .       .  542 

Care  of  Troops  and  Animals     .  543 

Common  and  Wai!  Tents    .       .  544 

Conical    Wall    Tents      ...  544 
To   Strike   Common,   Wall   and 

Conical    Wall    Tents      .      .  545 

To    Fold   Tents 546 

General  Remarks      ....  546 

Breaking    Camp        ....  547 

Captain,  Duties  of  the      ...  11 

Cell,     Gravity 250 

Reserve  Type  Dry  ....  248 

Cells,  Grouping  of      ....  256 

Ceremonies       .      .      .      .             .  221 

Checking  Telegraph  Messages    .  459 


INDEX 


PAGE 

Chest,  Pack  Set  Operating  .  .  408 
Cipher,  The  Route  ....  483 
Cipher  Disk,  The  ....  480 
Ciphsrs,  Telegraph  Code  Books 

and 480 

Circuit,  Connection  with  Antenna    345 

Transformer   Primary    .       .       .    39S 

Circuits,   Directly    Connected      .    376 

High   Frequency       ....    329 

High  Frequency  Transmitter  .    396 

Inductively  Connected  .       .      .    377 

Open  Oscillatory       ....    397 

Power  .       .       .      .       .      322,  394 

Radio   Receiving       ....    398 

Closed    Oscillating    or    Primary 

Circuit 329 

Coast    Defense: 

General .549 

Fortified    Positions        ...    550 

Mobile  Army 551 

Supports 554 

Aircraft,    Service    of      ...    556 

Coast  Guard 556 

Information    in  War      .       .       .    558 
Code   Books   and   Ciphers,   Tele- 
graph           .480 

Codes,   Letter: 

Infantry 476 

Cavalry 476 

Field  Artillery 477 

Coast  Artillery 478 

Shore-Tug    Signals        .      .      .478 
Code    List    of   Vessels      .       .       .487 
Code,  The  American  Morse  .       .    447 
The     International     Morse     or 

General  Service  ...  449 
Coding  of  Wave  Lengths  .  .  397 
Collective  Instruction  Mounted, 

Elementary   ....    112-116 

Alignments 112 

.    To  March   in   Line  .       .       .      .112 

To    Halt 113 

To  March  Backward      .       .       .113 

To    Oblique 113 

To    Turn    and    Advance      .       .113 
To   Form  Column   of   Fours   to 

the  Front 114 

To  Form  Column  of   Fours  to 

the  Flank 114 

To  Change  Direction     .       .       .114 
Being   in    Column   of    Fours: 
To    Move    to    the    Rear      .       .     114 
To  Form  Line  to  the  Front      .     115 
To   Form   Column   of  Twos    to 

the  Front       i       .       .       .       .115 
To    Form   Column   of    Files      .     115 
In    Column    of    Twos    to    Form 

Fours 115 

In    Column    of    Files    to    Form 

Fours     or    Twos      .       .       .     116 
Movements  in   Column   of  Twos    116 
In    Column    of    Fours,    to  .Dis- 
mount        116 

Manual    of    the    Pistol      .       .       .116 
Colors    (See   Standard,    The). 
Commands  and  Signals,   Drill     .      30 
Company  Dismounted,  The  .      .81-83 


Company    Dismounted,    The    (Cent.) 

General    Provisions       ...  81 

Posts    of    Officers,    etc.      .       .  81 

•  To   Form   the  Company      .       .  81 

Alignments 82 

To  Dismiss  the  Company  .      .  82 

Route    Order    and    at    Ease      .  82 

Condensers,   Transmitting     .       .  332 
Connections     for     Generator     of 

Pack    Set 407 

Contours 510 

Conventional      Signals     with 
Rockets,     Bombs,     Small 
Arms    and    Guns      .       .       .  485 
Counterpoise,   Antenna  and  .       .  404 
Coupling,     Mechanical     Illustra- 
tion  of 367 

Radiotelegraphic        ....  346 

Courtesy,  Military       ....  13 

Courtesies   in   Conversation  .       .  15 
Current    Terms,     Definitions    of 

Alternating          .  327 


Definitions  for  Drill  ....  28 
Depot  Signal  Troops  .  .  .133 
Desk  Telephone,  Local  Battery  278 

Detectors 382 

Directly  Connected  Circuits  .  376 
Discharge,  Measurement  of  Po- 
tential by  Spark  .  .  .  311 
Discharges,  Oscillatory  .  .  .  318 
Drill  Regulations  .  .  .  .24 
Dry  Cell,  Reserve  Type  .  .  .248 


Edison   Primary   Battery,   Direc- 
tions   for       .       .       .       .       .  254 
Electromagnetic   Induction    .       .  263 
Electromagnetic    Waves,    Radia- 
tion   of 310 

Electromagnetism        .       .       .  ' '•  1  262 

Electrostatic   Induction    .       .       .  263 

Emergency  Signals     .       .       4      ',  488 
Equipment   of   Personnel, 

Technical  .       .441 


Flag  Kits 428 

Flag      Signals      by      Permanent 

Hoist        .       .  ...    487 

Flags,  Signaling  by   Hand    .       .    470 
Flag,     Torch     and     Lantern,    .o'r- 
Beam  of  Searchlight  (with- 
out   Shutter)    Signaling   by    463 
Flash     Lantern,     or     Searchlight 
(with     Shutter)      Signaling 
with     Heliograph    or      .       .    465 
Field   Battalion,    The    (See    Bat- 
talion, Field). 

Field  Line*,   Establishing      .       .    492 

Field   Lines,   General   Provisions  .  524 

The  Wire  Cart  .       .       .       .       .524 

To  Clean  the  Wire  Cart    .       .    524 


INDEX 


PAGE 

Field  '  Lines    (Continued). 

Laying  the  Lines    ....  526 

Maneuvers  of  the  Battalions    .  328 

Stations    and    Call    Letters      .  528 

Maintaining    the    Lines      .       .  530 

Field  Radio   Pack  Sets     ...  402 

Field  Signal   Troops  ....  117 

Field,    Signal   Troops   in    the      .  491 
Field  Service,   Signal  Troops  in: 

Position 5 

Marches 521 

Camping  on   the  March      .       .  522 

Field   Wagon   Sets      ....  390 
Fields  of  Force,  Static     .       .       .305 

Magnetic 307 

Formation   Calls 32 

Frequency 320 

Frequency,      Wave      Train      or 

Spark 331 

Frequencies   in    Radio   Measure- 
ments         362 

Fuller  Battery 251 

Fuller    Battery,    Two- cell      .       .253 

Funeral  Escort 234 


Gaps,   Spark 341 

Quenched 343 

Garrison,  Instruction  in  .  .  452 
Gearing  for  Pack  Set  Generator  406 
General  Service  Code,  Interna- 
tional Morse  or  ...  449 
Generator,  Pack  Set  ...  405 
Government  and  Administration  11 

Gravity  Cell 250 

Ground   for   Radio   Sets  .       .       .358 

Guard  Mounting,  Company  .       .  548 

Guidon,    The 237 

Guns,    Signals    with  ....  485 

H 

Hand   Flags,   Signaling  by     .       .  470 

Heliograph,    The 431 

Heliograph,     Flash     Lantern     or 
Searchlight   (with  shutter), 

Signaling  with    ....  465 

High-Frequency   Circuits       .       .  329 
High- Frequency         Transmitter 

Circuits 3% 


Indicator,  Speed,   for   Pack   Sets  405 

Inductances,   Transmitting    .       .  336 
Induction,      Electrostatic      and 

Electromagnetic        .       .       .  263 

Induction    Telegraph    Set      .       .  300 

Inductively    Connected    Circuits  377 

Inspections 228-233 

Dismounted  Inspections      .       .  228 

Company  Inspection   .      .      .  228 

Battalion    Inspection         .       .  229 

Mounted  Inspections    ...      .      .229 

Company  Inspection   .       .       .  229 

Battalion  Inspection   ...  231 

Inspection       of       Shelter-Tent 

Camps 232 


PAGE 

Instruction  in   Garrison  ...  452 

Instructjon,    Object    of    Drill      .  34 

Instructions  for  Army  SirnaHng  445 
International    Morse   or   General 

Service    Code      ....  449 

Insulator,  Shelter-Tent  Antenna  418 

Interference  and  Static     .       .       .  379 


Keys,  Radio 326 

Kitchen,    Field        .  .     531 


Land    Forces,   Rules    and    Regu- 
lations of Ig 

Lantern,  The  Acetylene  .             .  436 
Letter  Codes: 

Infantry          .      .       .       .       .       .  476 

Cavalry 476 

Field   Artillery 477 

Coast    Artillery        .       .      .      .  478 
Shore-Tug  Signals   .       .       .       .478 
Lieutenant,  Duties  of  the      .       .  12 
Local    Battery    Transmission      .  267 
Locating   and    Operating   Visual 
Stations,    General    Instruc- 
tions   for 473 


M 


Magnetism 261 

Magneto 269 

Map  Reading,  Military     .       .       .    503 

Mast,   Sectional 404 

Messages,    Order    of    Transmis- 
sion of  Sealed    ....    446 
Mounted     Instruction,     Elemen- 
tary   Collective.     (See   Col- 
lective   Instruction.) 
Mounted,      The     Soldier.        (See 

Soldier  Mounted.) 

Morse  Code,  The  American  .      .    447 
The    International    or    General 

Service 449 


Object    of    Instruction      ...  24 

Ohm's    Law 243 

Operatjng  Chest  for  Pack  Set    .  408 
Operating  Visual  Stations,   Gen- 
eral   Instructions    for    Lo- 
cating  and 473 

Oscillating   (closed)    or   Primary 

Circuit 329 

Oscillation  Transformer   .       .       .  422 
Oscillations,      Mechanical      and 

Electrical 318 

Oscillatory   Circuit,  Open      .      .  397 

Oscillatory  Discharge*     ,       .       .  318 

Outpost  Company,  The    .      .    153-176 

Function   and   Employment      .  153 

Organization lS3 

The    Platoon: 

Tactical    Employment    ...  154 


INDEX 


PAGE 

Outpost    Company     (Continued). 
Composition        .  .    154 

Duties  of  Individuals  .  .  .155 
Numerical  Designator!  of 

Members 155 

Formations    and    Posts    of    In- 
dividuals       .       .  •    .       .       .     156 

Maneuver: 

General  Rules 156 

To  Form  the  Platoon  .  .  .158 
To  Dismiss  the  Platoon  .  .  158 
To  March  to  the  Front  .  .  158 

To    Halt 159 

To  March  to  the  Rear  .  .  159 
To  March  Obliquely  .  .  .159 
To  Change  Direction  .  .  .159 
To  Form  Column  to  the  Front 

from   Line 159 

To    Form    Line    to    the    Front 

from  Column  ....  160 
The  Double  Column  ...  160 
The  Single  Column  .  .  .161 
To  Align  the  Platoon  .  .  .161 
To  Open  and  Close  Ranks  .  162 
Route  Order  and  at  Ease  .  .  162 

Technical    Operation. 

The   Sections: 

Types  of -Sections  .  .  .  .165 
The  Headquarters  Section  .  165 
The  Switchboard  Section  .  .  166 
The  Telephone  Sections  .  .  167 

The   Company : 

Formation  of  the  Company  .  168 
Posts  of  Individuals  ...  168 

Maneuver: 

General  Rules 170 

To  Form  the  Company  .  .  170 
To  Dismiss  the  Company  .  171 
To  Align  the  Company  .  .  171 
To  March  to  the  Front  .  .  171 

To    Halt 171 

To  March  to  the  Flank  .  .  171 
To  March  to  the  Rear  .  .  172 
To  March  Obliquely  .  .  .172 
To  Change  Direction  .  .  .172 
To  Close  or  Extend  Intervals  .  172 

To    Form    Column    from    Line: 

To    the    Front 172 

To  the  Flank 173 

To  Form  Line  from   Column : 

To  the  Front 173 

To  the  Flank 173 

The  Double  Column  .  .  .174 
The  Single  Column  .  .  .174 
To  Form  the  Platoons  in  Line  174 
To  Form  Line  or  Column  .  174 
To  Open  and  Close  Ranks  .  174 
Route  Order  and  at  Ease  .  175 

Employment   in   the   Field    .      .    175 


Pack    Set,    191S   Radio      ...  420 
Pack  Sets,  Field  Radio    ...  402 
Packing  of  Field  Radio  Set  .      .  419 
Patrolling     and     Scouting,     Re- 
connaissance       ....  497 


PAGE 

Personnel          20 

Personnel,  Technical  Equipment 

of 441 

Physical  Training       .      .      .       52-69 

Setting  Up  Exercises     ...  S3 

Formations 54 

Recruit    Instruction        ...  58 

Second    Series        ....  60 

Third    Series 62 

Fourth    Series        ....  64 

Fifth  Series 66 

Sixth  Series 68 

Pistol,    Manual    of    (See    Arms, 

Instruction   with). 

Platoon,  Telegraph  or  Telephone  210 
Potential    by    Spark    Discharge, 

Measurement   of       ...  311 
Power   Circuits      ....    322-394 
Preconcerted    and    Conventional 
Signals     with     Rockets, 
Bombs,     Small     Arms     and 

Guns 485 

Preparatory    Signals     (Drill)      .  31 
Primary     and     Secondary     Bat- 
teries          242 

Primary    Circuit,    Closed    Oscil- 
lating  or 329 

Transformer 395 

Principles   of  Drill      ....  24 

Proficiency   Test    for   Companies  22 


Quenched-Gap    Transmitter, 

Theory  of 373 

Quenched-Spark    Gap,    Pack    Set  408 

Quenched    Spark    Gaps    .       .       .  343 


Radio    Company,    The      .       .     140-152 
Function   and   Employment      .     140 

Organization 140 

Duties  of  Individuals     .       .       .142 

The  Pack  Radio  Section: 
Composition         .....     142 

Formation 142 

Posts  and  Duties  of  Individuals    142 

Drill   of   the   Section: 

The  Guide 143 

The    Marchings        .       .       .       .143 
To  Form  to  the  Front  in  Two 

Lines 143 

To     Re-form     the     Section     in 

Normal  Formation  .  .  .143 
To  Form  in  Column  of  Files  .  144 
To  Re-form  in  Column  of  Twos  144 
To  Open  Station  ....  144 
To  Close  Station  .  .  .  .145 

The  Wagon  Radio  Section: 

Composition 145 

Formation 146 

Post  and  Duties  of  Individuals    146 
The  Wagon   Radio   Set      ..    146 

Drill  of  the  Seotkm-: 

Maneuver 147 

To  Open  Station      ....    147 
To  Close  Station      ....    148 


INDEX 


PAGE 

The    Radio    Platoon     ....  149 
The    Company  : 
Formation  of  the  Company  and 

Posts        .       .       .       .    ,  .       .149 
Drill  of  the  Company     .       .       .149 
Kmployment   in   the    Field: 

General 151 

Assignment      of      Sections      to 

Duty 151 

Selection  of  Station   Sites  .       .  151 
Instructions     for     Those     in 

Charge  of  Stations  .       .       .152 
Radiation      o  f      Electromagnetic 

Waves 310 

Radio  Set,   Efficiency  of  .       .       .  357 
Radio    Apparatus    of    the    Signal 

Corps 390 

Radiotelegraphy,  General  Theory  305 

Rank  and  Precedence  of  Officers  16 

Reactance  and   Rheostat   Control  325 

Receiver,  Wire  Telephone       .       .  272 
Receiving    by    Coding    of    Wave 

Lengths 401 

Receiving  Circuits,  Radio      .  -    .  398 
Receiving   Set,  Type   C     .       .       .423 

Type   D 427 

Receiving       Station,       Arrange- 
ments   at 375 

Reconnaissance,     Patrolling    and 

Scouting 497 

Relation   to  the  Line  of  the  Army  4 

Resonance 321 

Reviews 222 

Battalion    Review      ....  226 
Review     of     a     Battalion     with 

Closed   Intervals        .       .       .227 

Rheostat   and  Reactance  Control  325 
Ringer,    Telephone      .       .       .       .274 

Rockets.   Signals   witli       ...  485 

Route   Cipher,   The       ....  483 
Rules    and    Regulations   of    Land 

Forces              18 

Rules    for    Drill    Instruction   .  26 


School  of  the  Squad    . 
The    Squad    . 
To  Form   the  Squad 
Alignments    . 
To   Take   Intervals  . 
To   Assemble 


Saber.    Manual    of    the 

Saluting 

School    of    the    Soldier 

General     Provisions 

To    Assemble 

The   Rests      .... 

Eyes   Right    or   Left 

Facings 

Salute   with   the   Hand   . 

Steps    and    Marchings   . 

Quick  Time   .... 

Double    Time 


.  238 

.  13 
45-51 

.  45 

.  46 

.  47 

.  47 

.  47 

.  48 

.  48 

.  48 

.  49 

To  Mark  Time 49 

The  Half  Step 49 

Side    Step 49 

Back  Step 50 

To    Halt 50 

To  March  by  the  Flank       .       .  50 

To    March    to   the   Rear      .       .  50 

Change    Step 50 

Covering     and    .  Marching     on 

Points       .'.....  51 


PAGE 
70-75 

.       .  70 

.       .  70 

.       .  71 

.       .  71 

.       .  72 

Marchings 72 

To  March   to   the   Front       .       .  72 
To  March  by  the  Flank      .       .  73 
To  March   Obliquely       ...  74 
Turn    on    Moving    Pivot       .       .  74 
Turn  on  Fixed  Pivot     ...  75 
Scouting,     Reconnaissance,     Pa- 
trolling   and        ....  497 
Scaled      Messages,     Order     of 

Transmission    of       ...  446 
Searchlight   (with   Shutter),   Sig- 
naling     with      Heliograph, 

Flash  Lantern  or     ...  465 
Searchlight     (without     Shutter), 
Signaling    by    Flag,    Torch 

and  Lantern  or  Beam  of  .  463 
Secondary  Batteries  .  .  .  .257 
Secondary  Batteries,  Primary 

and 242 

Sectional   Mast 404 

Semaphore     Flags        .       .       .       .  428 

Service   Buzzer,   The.         .       .       .  290 

Service   Calls 32 

Sets,  Tractor  Radio  ....  427 
Shelter  Tent,  Radio  .  .  .  .418 
Signaling,  General  Instructions 

for  Army 445 

Signals,     Arm     (Drill)       ...  30 

Preparatory    Drill      ....  31 
Soldier   Mounted,   The      .       .      84-111 

Standard  Required   ....  84 

To  Stand  to   Heel     ....  84 

To    Stand    to    Horse      ...  84 

To   Lead  Out 85 

Alignments 85 

To  Mount   (Without  Saddle)     .  85 
Position    of    Soldier     (Without 

Saddle) 86 

Remarks  on   Position  of  Soldier    86 

The   Rests 87 

To  Dismount  (Without  Saddle)  88 
To       Lengthen       or       Shorten 

Reins 88 

To     Take     the     Reins     in     One 

Hand 88 

To   Adjust    the   Reins     ...  88 
To     Retake     Reins     in     Both 

Hands 89 

To  Drop  and   Retake   Reins      .  89 

To  Mount    From   Right   Side     .  89 

To  Dismount   on   Right   Side     .  89 

To  Dismiss  the  Squad  ...  89 

Gaits    of    Horses      ....  90 
Analysis  of  Gaits:     The  Walk, 

Trot,    Gallop        ....  91 
To  Mount   (with  Saddle)     . 
Position     of     Soldier     Mounted 

(with  Saddle)       .    ,  .       .       .  92 

Stirrups 93 

The   Double   Bridle   ....  93 


INDEX 


PAGE 

Soldier    Mounted,   The    (Continued). 
Instruction       with        Saddle, 

Double  Bridle  and  Spurs     .      93 
Riding      Without      Reins      and 

Stirrups *>4 

To  Dismount  (with  Saddle)  .  94 
Gathering  the  Horse  ...  95 
To  Move  Forward  ....  95 

To  Halt 95 

The  Half  Halt 96 

Changes   of   Gait      ....      % 
Extending    or    Reducing    Speed      97 
To    Form    in    Line    with    Inter- 
vals       97 

March     by     Flank     in     Column 

of   Files 98 

To  Change  Directions  ...  99 
The  Individual  About  ...  99 

To  Oblique 99 

To  Turn  on  the  Forehand  .       .  100 
To   Turn   on    the    Haunches       .  100 
To  Turn   on    Forehand   in   Re- 
verse           101 

To  Rein   Back 102 

To  Form  in  Line       ....  102 

To   Mount  in   Line  ....  103 

To  Dismount 103 

From  Line  to  Flank  in  Column 

of    Files 103 

From  Line  to  Front  in  Column 

of   Files 104 

Pass    from    the    Front    to    Rear 

of   Column 104 

Pass    from    Rear    to    Front    of 

Column 104 

To  March  in  Circle  ...  104 
Individual  Circling  .  .  .  .105 

To  Move  at  the  Slow  Trot      .  106 

To   Trot    Out 106 

Posting 106 

Changing      the      Diagonal       in 

Posting 107 

To  Gallop 108 

Pass    from     Canter     to     Gallop 

and   the   Reverse      .       .       .  109 
Pass  from  Gallop  or  Canter  to 

the    Trot 109 

Jumping 109 

To  Jump    the   Ditch      .       .       .111 
Elementary  Collective  Instruc- 
tion   Mounted    (See    Collec- 
tive   Instruction). 
Spark    Discharge,    Measurement 

of     Potential     by       ...  311 

Spark    Frequency,  Wave  Train  or  331 

Spark  Gaps 341 

Sketching    for    Beginners,    Mili- 
tary      517 

Semaphore,    Signaling    by    Two- 
Arm    .       .       .       .       .       .       .468 

Small   Arms,   Signals   with  .       .  485 

Sound    Signals 486 

Speed  Indicator  for  Pack   Sets  .  405 

Standard,    The 236 

Static  and  Interference.          .       .  379 

Storage  Battery,  General  Data  .  259 
Symbols,  Radio      .       .       .       .       .388 


Technical  Equipment  of  Person- 
nel        44] 

Telegraph    Battalion,   Tlu-      .    215-216 

Function 215 

Organization 215 

Formation    and     Posts    of    In- 
dividuals           216 

Maneuver 216 

Employment    of    the    Battalion  216 

Telegraph    Company,    The       .     183-214 

General     Provisions        ...  183 

Organization 183 

Duties  of  Individuals     ...  184 

The  Telegraph  Section: 

Composition 184 

Organization  and  Equipment  .  185 
Duties  of  Individuals  .  .  .185 
Numerical  Designation  of 

Members 186 

Formation   of  the   Section  .       .  188 

Posts     of     Individuals       .       .  188 
Distribution    of    Materiel    for 

Transport 188 

To   Form  the  Section     ...  188 

Section    Maneuver: 

To  Mount  and  Dismount     .       .  189 

To  Leave  the  Park  ...  189 
To  Conduct  the  Section  En 

Route 189 

To  Halt 190 

To   Dismiss   the   Section       .       .  190 

Technical    Drill: 

General  Provisions  ....  190 
To  Prepare  to  Open  Station  .  191 
To  Open  Station  ....  191 
To  Prepare  to  Close  Station  .  192 
To  Close  Station  ....  193 
To  Work  with  Reduced  Num- 
bers    195 

Line  Construction: 

Reconnaissance 196 

Use   of   Lance    Poles       .              .  1% 

To   Take   Up    the   Slack       .       .  196 

Guying   and    Guy 'Stakes     .       .  196 

To   Cut— In    Stations       ...  197 

Digging   Methods       .                   .  197 

Operation  and  Maintenance       .  197 

The   Telephone   Section  : 

Function         198 

Composition 198 

Organization 199 

Duties  of  Individuals  ...  199 
Numerical  Designation  of 

Members 200 

Formation   of  the  Section     .     .  201 

Posts  of  Individuals  ...  201 
Distribution  of  Materiel  for 

Transport 201 

To  Form  the  Section     ...  201 

Maneuver 201 

Technical    Drill: 

General    Provisions       ...  201 

Preliminary  Reconnaissance     .  202 

To  Prepare  to  Open  Station     .  203 

To    Open    Station     ....  203 


INDEX 


PAGE 

Technical    Drill     (Continued"). 

To  Prepare  to  Close  Station     .  204 

To  Close  Station      ....  204 
To   Work    with    Reduced    \iun- 

bers 205 

Line   Construction: 

Use   of   Lance    Poles    '  .       .       .  207 

Cabling 207 

Depth  of   Poles  .....  207 

Terminal    Poles         ....  208 

Guying  and  Guy  Stakes       .       .  208 

Insulators 208 

To  Take  Up  Slack   ....  208 

Operation  and  Maintenance  .       .  209 

Underground  Construction     .        .  209 

Trenching 209 

Cabling 210 

Covering 210 

Guards 210 

The    Platoon: 

Function   and   Organization       .  210 

Formations 210 

To  Form  the  Platoon     .       .       .211 

Maneuver 211 

Technical   Drill 211 

Methods  of  Employment     .       .  211 
The   Company: 

Formations  and  Posts  of  Indi- 
viduals       212 

To    Form    the   Company       .       .  212 

To  Dismiss  the  Company  .       .  213 

Maneuver 213 

Employment    in    the    Field       .  214 

Telegraph    Set,    Induction      .       .  300 

Telegraph    Signal    Troops       .       .  181 

Telegraphy  and  Telephony     .       .  242 

Telegraphy,  Instruction  in  .  452 

Telephone,    Common    Battery       .  281 

Telephone   Instrument  Types       .  275 

Telephone,  Local  Battery  Wall  .  277 

Local    Battery    Desk      .       .       .278 

Receivers    for   Radio      .       .       .  386 

The   Camp 287 

Theory   of  the    .       .       .       .       .  265 

Telephone  Signals,   Conventional  490 
Telephone      Section,     The      (See 

Telegraph    Company). 
Telephony,    Instruction    in     .     242-261 
Tent,    Radio    Shelter  .       .       .       .418 
Test    for    Companies,    Proficiency    22 
Torch    and    Lantern   or   Beam   of 
Searchlight  (Without  Shut- 
ter),   Signaling    by    Flag     .  463 
Tractor    Sets    (Radio)      .       .       .427 
Transformer  Primary  Circuit       .  395 
Transformer,  Principle  of  the      .  264 

Transformers 322 

Transmission,    Local    Battery       .  267 
Common  Battery       ....  267 
Transmission     of     Military     In- 
formation         442 

Transmitter,  Telephone   ...  2 

Transmitting  Condensers       .       .  332 

Tug    (Shore)     Signals      .       .       .478 

Tuning  of  Pack  Set     .  .       .  411 

Of  Transmitting   Sets  ...      .367 

With   Wave  Meter  .       .       .       .371 


PAGE 

Without  Wave  Meter    ...  370 
Two-Arm    Semaphore,    Signaling 

by 468 

Two-Cell    Fuller   Battery         .       .  253 

U 

Uniforms 19 

Units,   Systems   of   Radio- 
telegraphic     314 


Very  Pistol 486 

Visual    Signaling    Equipment       .  428 

Visual    Signaling    in    General       .  461 
Visual   Stations.  General  Instruc- 
tions     for      Locating      and 

Operating       .  473 

Visual   Stations,    Instruction   for  452 
Voltaic    Cell,    The      .       .       .       .242 

W 

Wagon   Sets,   Field  Radio      .       .  390 

Wall  Telephone,  Local  Battery  .  277 

Wand,  The 428 

Warning   Calls 32 

Water    Supply 530 

Wave   Length,   Natural   or    Fun- 
damental          364 

Wave  Lengths 360 

Wave  Lengths,  Coding  of      .       .  397 

Wave  Meter     ......  362 

Wave    Meter,    Calibrating   W'ave 

Lengths  by 387 

Wave  Train  or  Spark  Frequency  331 
Waves,     Radiation     of     Electro- 
magnetic           310 

Wire    Company,     The      .       .     118-139 

Function    and    Employment       .  118 

Organization 118 

Duties  of  Individuals     .       .       .  119 
The  Section: 

Composition 120 

Formation 120 

Posts     and     Duties     of     Indi- 
viduals       120 

Drill   of   the   Section : 

The   Guide 122 

To    March    to    the    Front     .       .  122 

To  Halt 122 

To   Change   Direction     ...  122 

To    March    to    the    Rear       .       '.  122 
To   March   Obliquely              .       .122 

To  Form  Section  Into  Line       .  123 
To  Re-form  Section  in   Normal 

Formation 123 

To    Form   in   Column   of   Twos 

or  Files 123 

To  Re-form  in  Column  of  Fours  123 

To  Open   Station      ....  123 
Laying  the  Wire      .       .       .       .124 

To    Close    Station     ....  124 
Recovering  the  Wire     .       .       .125 
The  Wire  Platoon: 

Composition 125 

Formation 125 

Post  and  Duties  of  Individuals  126 

Drill  of  the   Platoon      ...  126 


INDEX 


PAGE 

The'.  Company : 

Formation  of  the  Company       .  126 

Posts  of  Individuals             .       .  128 

Drill    of   the    Company: 

The   Guide 128 

Gaits         129 

To    Form    the    Company 

Mounted 130 

To  Dismiss   the  Company   .       .  130 

To   Align    the    Company       .       .  131 

To  March   to  the  Front      .       .  131 

To  Halt 131 

To  March  by  the   Flank       .       .  131 

To  March  to  the  Rear  .  .  131 
To  March  Obliquely  .  .  .132 
To  Change  Direction  .  .  .132 

To  Close  or  Extend  Intervals  133 
To  Form  Section  Column  to 

Front 133 

To    Form    to    Front    from   Sec- 
tion   Column        ....  133 
To  Form  Line  to  Right   (Left) 

from   Section  Column  .       .  133 


PAGE 

To    Form   Sections   in    Line      .     134 
To     Re-form     Sections     in     the 

Normal    Formations       .       .     134 
To  .  Form    Platoon    Column    to 

Front  from  Section  Column     I.i4 
To    Form     Platoon    Column    to 

the      Flank      from      Section 

Column 134 

To    Form    Section    Column    to 

the     Front      from      Platoon 

Column 135 

In      Line,     to      Form      Platoon 

Column    to    Right      .       .       .     135 
In    Platoon    Column,    to    Form 

Line  to   Right     ....     135 
Route  Order  and  at  Ease  .       .135 
Employment  in  the   Field: 

General 136 

On   the  March 136 

In    Battle 137 

In   Camp 137 

Reserve   Wire   Carts       .       .       .137 
Reconnaissance         .       .       .       .137 


Equipment 
Section 


A  Signal  Aid  to  Corps  Efficiency 

IN  place  of  the  inaccurate  and  laborious  writing 
out  by  hand  of  everything  from  reconnaissance 

o     *j-»     s*l4»t*is-»ri  1      rt  *»*1  1  lo 


data  to  clerical  details 

CORONA 

has  found  instant  favor  in  all  sections  of  the  Signal 
Corps.  Because  of  its  light  weight  and  durability, 
it  is  especially  popular  in  the  Aviation  Section, 
where  a  large  number  of  Coronas  are  already  in  use. 

Sturdily  built   to  withstand    severe    field  service, 

Corona  weighs  but   six  pounds — 9 

pounds  with  case — -folds  into  its  case 

when  not  in  use,  and  packs  11^  by 

10    by  4^    inches.      Exceptionally 

simple  to  operate. 

Corona  and  case,  complete,  cost 
$50.  Light  weight  folding  stand  at 
slight  extra  cost.  Ask  for  folder. 

CORONA  TYPEWRITER  CO.,  Inc. 

Groton,  N.  Y. 
Agencies  in  all  principal  cities. 


The  MILITARY  DAYLO 


When  dispatches  come  to  you  in  the  field  at 
night  here's  the  light  to  read  them  by.  .Carry 
an  Eveready  Military  Daylo  with  you  every  night 
— for  signaling,  to  show  up  the  dangers  of  the 
darkness,  and  for  protection. 

You   can   use   this   Eveready   Military  Daylo 
without  interfering  with  the  work  of  either  hand. 

It  may  be  hung  on  the  but- 
ton of  your  coat ;  the  but- 
ton piece  may  be  turned 
around  to  form  a  belt  clip 
and  the  Daylo  thus  fas- 
tened on  the  belt;  or,  it 
may  be  hung  upon  a  nail  in 
the  tent  pole  or  upon  what- 
ever is  convenient. 

Sold  by  the  better  electrical, 
hardware,     drug,     sporting 
goods,   stationery  and  jewelry 
stores      every- 
where.    Insist  on 
Eveready  Tung- 
sten batteries  for 
renewals. 

AMERICAN  EVER  READY  WORKS 

of    National     Carbon    Co.,     Inc. 

LONG    ISLAND    CITY,    N.    Y. 

Chicago  Atlanta  San    Francisco 


Model  280 

Portable 

Triple  Range 

Volt -Am  meter 


Indicating  Electrical 
Measuring  Instruments 

are  recognized  throughout  the  world 
as  representing  the  highest  achieve- 
ment in  the  Art  of  Electrical  Meas- 
urement. 

We  are  prepared  to  furnish  any 
type  of  Indicating  Electrical  Meas- 
uring Instrument  carried  in  the  Sig- 
nal Corps  work.  Write  for  particu- 
lars regarding  instruments  to  meet 
whatever  requirements  you  have- 

Weston  Electrical 
Instrument  Co. 

129  Weston  Ave.,  Newark,  N.  J. 

23  Branch  Offices  in  the  Larger  Cities. 


Model  167 
Single  Phase 

and  D.  C. 
Switchboard 
Wattmeter 


KHAKI  WATCH 


ft  EG.   U.S.  PAT.  OFF. 


The 
Ideal 
Watch 
for  the 
Soldier 


Always   sold   in   "Khaki"  Box.     Insist  on 
securing    the    box     to    avoid     imitations. 


Prestige 


WALTHAM     MOVEMENT 


Accuracy 


Only  the  movement  that  will  stand  up-  under  the  rough 
usage  of  Military  life  is  of  value  to  the  Soldier.  Your 
soldier  must  have  the  best.  Waltham  is  known  the  world 
over  for  its  accuracy  and  durability,  and  is  the  standard 
by  which  other  watches  are  judged. 

NON-EXPLOSIVE 
UNBREAKABLE    GLASS 

Protects  the  watch — Cannot  break  or  crack — Is  not  a 
Nitro-Cellulose  product,  which  is  dangerous.  It  is  neces- 
sary and  safe.  Does  away  with  clumsy  grilled  protection 
for  crystal  which  hinders  movement  of  sleeve.  Bezel  Pat., 
Sept.  11,  1917. 

RADIUM     DIAL 


"Cravenette"  Finish 

Webbing 

Moisture  proof.  Stronger 
and  more  comfortable  than 
leather.  Matches  uniform 
of  Soldier  or  Sailor.  Khaki 
Color,  Blue,  Black  or  White. 

Write   for  booklet.     "The 


"No    FUM* 
Strap 

Slips  over  hand  as  a  loop. 
Therefore  cannot  be  dropped 
when  putting  on.  Leaves 
no  loose  strap  end  to  catch 
in  sleeve.  Clasp  Pat.,  July 
25,  1916;  Oct.  24,  1916. 

Watch  in  the  Trenches." 


JACQUES  DEPOLLIER  &  SON, 

Manufacturers    of    High    Class    Specialties 
for  Waltham  Watches 


Strike  Again! 
It  Can't  Crack! 


15  MAIDEN  LANE 
DUBOIS  WATCH  CASE  CO- 


NEW  YORK 

EST.   1877 


Combination  Signaling  Practice  Set 

For   Learning  Telegraph   Code. 


This  outfit  is  used  at  the  Annapolis  Naval  Academy  in  the  instruction 
given  future  naval  officers.  It  enables  the  student  to  become  proficient 
in  audible  and  visual  signals  because  it  is  equipped  with  a  buzzer  for 
the  sound  and  a  lamp  for  light. 

It  consists  of  wireless  key,  high  pitched  buzzer,  miniature  socket  and 
base  with  special  miniature  lamp,  switch  for  transferring  the  current  from 
buzzer  to  lamp,  three  binding  posts  mounted  on  a  highly  finished  wood 
base.  Price  includes  RED  SEAL  Dry  Battery  and  Cord.  An  exceedingly 
acceptable  gift  not  only  for  the  man  in  the  service  but  also  for  any  one 
who  has  a  desire  to  learn,  general  signalling.  Instructions  included. 
List  No.  52 — Combination  Signalling  Practice  Set  with  Battery 

Cord,    price,    $3.60 

Students  Wireless  Practice  Set 

With  Induction  Coil. 


For  students  of  Wireless  telegraphy,  this  is  an  exceptionally  desirable 
outfit  as  the  induction  coil  permits  the  operator  to  use  his  standard 
radio  head  set  as  if  he  were  receiving  bona-fide  radio  signals.  The  note 
emitted  is  clear  and  distinct.  This  makes  an  ideal  present  to  the 
enlisted  man  or  officer  who  desires  to  acquire  a  working  knowledge  of  the 
codes  which  can  be  done  in  his  spare  moments.  Price  includes  RED 
SEAL  Dry  Battery  and  Cord.  It  is  similar  to  the  No.  52  in  construction 
with  the  addition  of  an  Induction  Coil. 
List  No.  53— Students  Wireless  Practtce  Set,  Price $4.05 

>!?%^ 

SEND  FOR  CATALOG  No.  C  28. 

It  is  pocket  size,  contains  248  pages,  with  over  1,000 
illustrations,  and  describes  in  plain,  clear  language  all 
about  Bells,  Push  Buttons,  Batteries,  Telephone  and 
Telegraph  Material,  Electric  Toys,  Burglar  and  Fire 
Alarm  Contrivances,  Electric  Call  Bells,  Electric 
Alarm  Clocks,  Medical  Batteries,  Motor  Boat  Horns, 
Electrically  Heated  Apparatus,  Battery  Connectors, 
Switches,  Battery  Gauges,  Wireless  Telegraph  Instru- 
ments, Ignition  Supplies,  etc. 

Manhattan  Electrical  Supply  Company,  Inc. 

NEW  YORK:    17  Park  Place        SAN  FRANCISCO  OFFICE:  604  Mission  St. 

ST.  LOUIS:    1106  Pine  St.  CHICAGO:    114  S.  Wells  St. 

Factories:  JERSEY  CITY,  N.  J.  ST.  LOUIS,  MO.  RAVENNA,  O, 


A   Knife   Worth  Owning 

Built  to  Fight  Battles  With 

A  GOOD  KNIFE  is  very  much  like  a  good 
man  inasmuch  as  it  must  possess  char- 
acter, stability  and  a  healthy  constitution  to 
stand  the  hard  knocks  it  is  sure  to  receive  in 
this  busy  world.  Take,  for  instance,  the  knives' 
known  as  the 

"Hammer    Brand" 

you  will  always  find  them  ready  for  duty  and 
they  actually  cut  their  way  through  the  tough- 
est problems  they  are  put  up  against.  A 
"Hammer  Brand"  knife  in  your  pocket  or  at- 
tached to  your  belt  is  always  ready  to  cut 
away  miles  of  insulation  without  a  whimper. 

In  camp,  on  the  march,  in  stress  of  active 
service  or  in  civil  life  you  can  always  be  sure 
of  a  trusty  companion  and  an  able  assistant 
when  you  have  a  "Hammer  Brand"  knife  with- 
in reach. 

When  buying  your  next  knife  don't  just 
ask  for  a  knife  but  say  "Hammer  Brand," 
please,  and  then  you'll  enjoy  the  satisfaction 
of  putting  your  money  into  a  tool  with  a  hun- 
dred uses  and  with  years  of  good  service 
ahead  of  it. 

Let  a  "Hammer  Brand"  knife  fight  your  cut- 
ting battles  for  you. 

New  York  Knife  Company 

Walden  New  York 


Out  of  the  experienced  past, 
into  the  exacting  present, 
KERITE  through  morethan 
a  half-century  ofsuccess- 
ful  service, continues 
as  the  standard  by  which 
engineering  judgment 
measures  insulating  value 


NEW  YORK 


CHIC  A.G  O 


LEARN  THE  CODE 
WITH  THE  OMNIGRAPH 

The  Omnigraph  Auto- 
matic Transmitter  will 
teach  you  the  Wireless 
and  Morse  Codes  in  half 
the  usual  time  and  at 
trilling  cost.  Connected 
with  buzzer  or  sounder. 
The  Omnigraph  will  send 
you  unlimited  Continen- 
tal or  Morse  Code  mes- 
sages  at  any  speed  you 
desire.  Used  by  the  U. 
S.  Govt.  and  leading 
Universities,  Colleges 
and  Telegraph  Schools 
throughout  the  country. 

Send   for   free   catalog   describing  3   models    ranging   in    price    from   $8.00   to 

$20.00. 

THE  OMNIGRAPH  MFG.  CO.,  39  CORTLANDT  ST.,  N.  Y. 

Major  White,  author  of  this  book,  says:  "The  prominent  training' 
schools  for  the  past  12  years  have  found  the  OMNIGRAPH  the  one  real 
helper  that  turns  out  finished  men.  The  U.  S.  Govt.  finds  the  OMNIGRAPH 
•o  practical  it  places  a  large  number  of  new  machines  in  use  every  year." 


For  the  Camp  or  Field  of  Action. 

The  Signal  Corps  Man  Needs 
This  Pair  of  "Red  Devil"  Pliers 

Its  quality  is  symbolic  of  the  Signal 
Corps'  efficiency — always  dependable  and 
ready  for  instant  action — made  of  drop 
forged  tool  steel  with  hardened  and 
toughened  cutting  edges,  built  to  stand 
the  hard  knocks  and  give  continuous  ser- 
vice every  hour  of  the  day. 

Style  No.  50.  Made  in  4,  5,  6,  7  and  8- 
inch  lengths.  At  all  reliable  dealers  or 
from  us.  Send  $1.30  for  a  sample  7-inch 
tool. 

Tool   literature   free   on   request. 

SMITH  &  HEMENWAY  CO.,  Inc. 

117  COIT  STREET,     IRVINGTON,  N.  J. 


UNIVERSITY  OF  CALIFORNIA  AT  LOS  ANGELES 

THE  UNIVERSITY  LIBRARY 
This  Ixjok  is  DUE  on  the  last  date  stamped  below 


JULl  3  1961 


Form  L-9 
20m-l,'  41(1122) 


• 

LARY 


UC  SOUTHERN  REGIONAL  LIBRARY  FACILITY 


UG 

573 

W58m 

cop.  2 


